Chapter 3 19 Pine Species of California Smith 

Table 3-36—Average monoterpene composition of the trees in three stands of P. monticola in 

three National Forests; n = number of trees in stand 

National Forest 

Component Deschutes Shasta Eldorado 

n=16 n=60 n=104 

--------------------------------- percent 1 ----------------------------

Nonane 1.6 1.1 1.5 

α-Pinene 71.1 82.5 53.0 

Undecane 2.0 3.0 5.6 

ß-Pinene 14.1 9.1 21.7 

3-Carene 3.1 0 7.0 

Sabinene 1.0 0.4 0.2 

Myrcene 1.2 1.0 1.9 

Limonene 1.6 2.3 6.4 

ß-Phellandrene 3.5 0.4 1.6 

Terpinolene 0.7 0.2 0.7 

1

 Normalized. 

Table 3-37—Intervals of the frequency distribution of the normalized percentages that were 

used to define the low (0), medium (1), and high (2) modes of the five noted monoterpenes of P. 

monticola 

Mode 

Monoterpene 0 1 2 

------------------------------- intervals in percent 1 ---------------------------

α-Pinene 0 - 44 45 - 62 63 - 100 

ß-Pinene 0 - 10 11 - 20 21 - 100 

3-Carene 0 - 10 11 - 30 31 - 100 

Myrcene 0 - 2 3 - 5 6- 100 

Limonene 0 - 2 2 - 10 11 - 100 

1

 Normalized. 

90 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-27—Frequency distribution 

of the amount of the 11 noted xylem 

monoterpenes and related hydrocarbons in stands of P. monticola in the three 

National Forests listed on the right; each 

dot is measurement of one tr

 indicates each represents 

trees; ▲ is average of stand. 

ee except 

where n 

(fig. 3-27 continues on the next 4 pages). 

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Chapter 3 19 Pine Species of California Smith

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Chapter 3 19 Pine Species of California Smith 

Table 3-38—Coded types of composition of P. monticola, their occurrence (n) in all trees, and their average actual composition 

Monoterpenes2 

Code 1 n und α-p cam ß-p car sab myr lim ß-ph ter 

percent 3 

00200 1 0.9 42.3 1.5 7.9 38.7 0 1.7 0.6 3.2 2.8 

00201 1 0.6 36.6 3.9 10.1 36.4 0 1.7 7.2 1.4 2.1 

00212 1 2.0 28.3 5.1 6.0 33.8 0 2.5 16.6 1.5 4.2 

01200 3 0.8 34.7 6.2 15.3 37.1 0 1.7 0.5 1.4 2.1 

01201 5 1.7 36.5 5.7 11.9 34.3 0 1.6 4.6 1.4 2.2 

01210 3 1.5 37.8 6.0 15.4 31.5 0 3.9 0.7 0.7 2.3 

01211 1 5.2 26.0 9.3 15.5 35.5 0 2.6 3.0 0.8 2.0 

02000 5 1.3 37.6 5.4 44.0 1.9 0.1 1.3 1.2 5.6 0.8 

02001 1 4.3 37.2 11.6 34.6 0 0 1.3 9.1 0.5 1.2 

02002 1 0.3 39.9 5.2 31.2 0 0 1.5 20.1 1.8 0 

02021 1 2.2 41.4 10.7 34.6 0 0 5.8 4.6 0.6 0 

02200 2 0.8 28.1 4.2 16.2 43.1 0 1.9 1.2 1.3 3.3 

02201 2 0.6 27.1 2.6 24.8 36.0 0 1.9 4.2 1.1 1.8 

10002 1 2.7 62.0 9.0 10.2 0 0 1.3 14.5 0 0.2 

10022 1 1.4 60.2 3.9 9.9 0 0 5.6 17.7 0.4 0 

10122 1 1.6 48.5 5.7 3.5 11.2 0 6.3 21.7 0 1.2 

10200 1 2.6 56.6 5.4 5.4 26.7 0 1.2 0.3 0.4 1.1 

11000 1 1.3 52.0 3.5 19.0 0 8.6 0.8 0.6 8.6 4.3 

11001 4 2.0 61.0 5.3 17.0 0 3.1 1.0 6.5 2.0 1.2 

11002 6 1.3 54.8 6.9 17.4 0.6 0 1.4 16.6 0.8 0.2 

11021 1 2.0 58.5 5.5 15.8 0 0 6.0 7.1 4.0 0.5 

12000 14 1.4 55.3 4.6 35.2 0 0.3 1.2 1.0 2.7 0.3 

12001 10 1.7 52.3 5.3 29.6 1.0 0 1.3 6.9 1.5 0.3 

12002 7 1.3 48.4 5.2 25.8 0.5 0.1 1.4 16.3 0.9 0.1 

12011 4 2.8 51.8 8.3 27.9 0 0.2 3.7 5.0 0.8 0.4 

12021 2 2.5 47.5 6.2 23.1 0 0.4 8.6 8.8 1.6 1.4 

12101 1 0.0 53.7 3.0 23.8 12.4 0 1.3 5.3 0.4 0 

20000 36 1.2 89.1 2.9 6.5 0 0.3 0.9 1.1 0.4 0.1 

20001 13 1.2 84.3 2.8 6.3 0 1.3 1.2 4.4 0.1 0.5 

20002 5 1.2 75.1 2.5 6.0 0 0.4 1.0 14.7 0 0.1 

20020 1 0 97.9 1.7 5.7 0 0 5.7 0 0.7 0 

21000 19 1.3 78.9 3.6 14.7 0 0 0.9 1.2 0.8 0.2 

21001 8 2.5 66.8 6.9 15.8 0.5 0 1.2 5.6 0.6 0.1 

21002 2 0.5 68.1 5.4 13.1 0 0 1.0 11.1 0.5 0.4 

21010 1 1.3 66.8 4.7 18.4 0 0 4.1 1.4 0.8 2.2 

21011 2 0.9 66.1 5.1 17.0 0 0 3.8 6.8 0.4 0 

21120 1 2.7 68.4 4.7 14.8 0 0 7.5 1.0 0.9 0 

22000 9 1.3 70.1 3.8 24.0 0 0 1.0 0.8 0.7 0 

22001 1 1.1 64.3 2.8 22.1 0 0 2.2 6.7 0.9 0 

22002 1 1.4 70.2 4.5 11.7 0 0 1.7 10.5 0 0 

1 From left to right: α-pinene, ß-pinene, 3-carene, myrcene, limonene for code types. 

2 Actual composition: undecane, α-pinene, camphene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, terpinolene. 

3 Normalized. 

96 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
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Smith 19 Pine Species of California Chapter 3 

Table 3-39—Maximum and minimum percentage for individual monoterpenes in the xylem resin of P. 

monticola report in two sources: (A) derived from this report, (B) derived from Zavarin and others (1990) 

A B 

n=1801 n=191 2 

Monoterpene Maximum Minimum Maximum Minimum 

-------------------------------------------percent 3 

Nonane 5 0 0 0 

α-Pinene 94 20 95 4 

Undecane 12 0 46 0 

ß-Pinene 55 0 51 0 

3-Carene 55 0 68 0 

Sabinene 16 0 28 0 

Myrcene 11 0 14 0 

Limonene 23 0 68 0 

ß -Phellandrene 25 0 18 0 

Terpinolene 6 0 0 0 

1

 Three stands, southwest portion of range. 

2

 Twenty stands, throughout the range. 

3

 Normalized. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 97 
Chapter 3 19 Pine Species of California Smith 

Figure 3-28—Occurrence 

of 41 coded types of composition in three stands of P. 

monticola; frequency of 

types normalized for each 

stand; see table 3-38 for 

actual average composition 

of coded types. 

98 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smi

th 19 Pine Species of California Chapter 3 

#13. Pinus muricata D. Don. (Bishop pine)

P. muricata is essentially limited to California with its southern limits just 

extending into northern Baja California (fig. 3-29). It is a coastal species, 

generally found within just a few miles of the ocean; but it has been successfully

planted at the Institute of Forest Genetics (IFG) in the Sierra Nevada foothills 

more than 100 hundred miles from the ocean. It has also been successfully 

planted in Australia and New Zealand. 

The study of the xylem monoterpenes of P. muricata is a most interesting 

story. In 1947, Mirov (1961) first examined resin from trees from the northern 

portion of the range that were growing at the Institute of Forest Genetics and 

found the xylem monoterpene portion to be near-pure α-pinene. Then Duffield 

(1951), finding sharp morphological differences between the northern, central, 

and southern stands, as well as those on the Channel Island, proposed four 

.species or four varieties. Mirov (1961) then looked at trees growing at IFG 

which represented the four groups proposed by Duffield. Sample size was 

adequate only for optical rotation analysis, but the analysis showed that the 

four groups had large differences in optical rotation of the total turpentine 

sample, suggesting large differences in monoterpene composition. 

Forde and Blight (1964), with the aid of gas chromotography, analyzed 

trees from the four locations for xylem monoterpenes (table 3-40) and found 

four types of stands much like those proposed by Duffield: (1) northern stands 

with large amounts of α-pinene; (2) central stands with large amounts of 3-

carene; (3) southern stands with large amounts of sabinene and terpinolene; 

and (4) Channel Island stands with composition much like the southern stands 

but with some trees having considerable ß-pinene. The Channel Island stands 

are sometimes called P. remorata, but Griffin and Critchfield (1972) do not list it 

as a separate species. Most of the trees sampled by Forde and Blight (1964) were 

growing in Australia from seed collected at the designated locations in 

California. Blight and McDonald (1963) were the first to report moderate to 

large amounts of sabinene in the xylem resin of a pine in P. muricata. Since then, 

sabinene has been reported in a number of pines. 

Mirov and others (1966) sampled native stands more intensively and 

extensively. Their results confirmed the results of Forde and Blight (1964). 

Mirov and others (1996) also found evidence of a very narrow transitional 

stand between the northern and central regions near Annapolis (table 3-40). 

Their sampling of the Channel Islands showed much greater variation than 

Forde and Blight (1964). This variation could either have been caused by a 

larger sample, or their sampling included both Santa Cruz and Santa Rosa 

Islands. A substantial amount of ß-pinene was found in the Channel Island 

trees, but Forde did not find ß-pinene in trees on the Channel Islands. Mirov 

and others (1966) also reported moderate amounts of myrcene, limonene, and 

ß-phellandrene which have not been reported in other publications. 

I analyzed the resin from a stand of 106 trees at Pt. Reyes, which is in the 

central region as defined by Mirov and others (1966), in order to get a better 

understanding of local variation and of the kinds and frequency of types of 

composition in a small stand in the central region of P. muricata. The range of 

values for α-pinene and 3-carene was generally greater than that reported from 

smaller stands in the same geographic area by Forde and Blight (1964) and 

Mirov (1961) (table 3-40). Since Forde and Blight (1964) and Mirov and others 

(1966) did not give averages for their stands, a comparison cannot be made. 

Mirov and others (1966) found trees with as much as 95 percent α-pinene in the 

central region; neither Forde and Blight (1964) nor my sampling found α­

pinene in excess of 88 percent. Little or no difference in composition was found 

between a basal tree sample and one at 20 feet (see table 8-1). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 99 
Chapter 3 19 Pine Species of California Smith 

Figure 3-29—Distribution of 

Pinus muricata in California, taken 

from Griffin and Critchfield 

(1972); regional types indicated by 

solid line on the left. 

100 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smi

th 19 Pine Species of California Chapter 3 

The frequency of the individual components in the 106 tree stands suggested 

a trimodal distribution for both α-pinene and 3-carene (fig. 3-30). Estimates were 

made of the limits of the three modes for α-pinene and 3-carene (table 3-41). When 

the composition of the individual trees was coded according to the modal 

distribution criteria for α-pinene and 3-carene, six types of composition, out of the 

nine possible ones, were found in the 106 trees (table 3-42). 

It is clear (table 3-42) that 89 percent of the trees were of three coded types: 

0-2, 1-1, and 2-0, where the first number is α-pinene and the second is 3-carene. 

The other 11 percent were of three other types, 1-2, 2-1, and 0-1. It is possible 

that there were only the first three types, and the other three types were 

artifacts of the analytical and coding procedures, or were the result of the 

aggregate biological variation or minor effects. 

It might be assumed that all the trees in this central region of P. muricata 

had a (1-1) set of alleles for 3-carene, and that the variation encountered was 

caused by varying sets of alleles for α-pinene. However, under such conditions 

one would expect equal amounts of α-pinene and 3-carene in some trees, where 

both have a (1-1) set of alleles. Such was not the case. The alternative was to 

consider nonequal competition for the C-5 precursor or a very strong 

environmental effect. It appears that the genetics of α-pinene and 3-carene 

might be different in P. muricata than in other pine, which is highly unlikely, or 

some other unknown factor is present. 

Ten intraspecific hybrids of P. muricata growing at IFG were examined 

(table 3-43). The results did not fully agree with the regional subdivisions. The progeny of Inverness x Fort Ross, high 3-carene x high α-pinene, were as 

expected, with mixtures of α-pinene and 3-carene, but the progeny of Monterey 

x Fort Ross, high 3-carene x high α-pinene, were not as expected. One would 

again expect mixtures of α-pinene and 3-carene; instead the progeny are near-

pure α-pinene. The Monterey parent could have been misidentified; or could 

have been a high α-pinene P. radiata, or a P. attenuata x P. muricata from the 

northern region could have been the female parent. Likewise three of the 

progeny of San Vicente x Monterey had no sabinene where one would expect 

considerable sabinene. There also may be much more local variation within the 

regions than had been reported. An experimental breeding program of P. 

muricata with specific types of composition would certainly be recommended. 

Forde and Blight (1964) used steam distillation of the whole resin followed 

by GLC analysis for some of their samples, and results were very similar to 

samples prepared differently. This, of course, differed sharply from results by 

steam distillation of mill-ground xylem reported by Anderson and others 

(1969, 1970). Their results differed sharply from results obtained by using the 

sample preparation procedures reported in this volume and by others for P. 

attenuata, P. monophylla, and P. quadrifolia. As far as I can determine, the only 

difference between the two procedures was that Forde and Blight (1964) and 

Mirov (1961) used gross resin while Anderson and others (1969, 1970) used 

mill-ground xylem followed by steam distillation. 

#14. Pinus ponderosa Dougl. ex Laws. (ponderosa pine) 

P. ponderosa is one of the most valuable, widespread, and variable pines in the 

world. In western North America it extends from southern Canada into 

northern Mexico and from the Pacific Ocean to the Great Plains (fig. 3-31). 

Within that geographical definition it is noticeably absent from an area where 

one would expect it: western Wyoming, southeastern Idaho, and southwestern 

Montana. An illustration of the wide range of sites it occupies is the associated 

plants at extremes of its distribution: it can be associated with redwood on the 

west coast, with larch in the north, with Great Plains grasses in the east, and 

with cactus in the southwest. Details of its distribution, growth, habits, and 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 101 
Chapter 3 19 Pine Species of California Smith 

Table 3-40—Range of five monoterpenes in stands of P. muricata in California or originating from seed collected in California as reported by different 

researchers; n = number of trees 

Monoterpene 3 

Regional Type 

Northern 

Transition 

Central 

Southern 

Channel Islands 

Locality 1 

Trinidad Head to Fort Bragg 

2 mi. N. of Annapolis 

Annapolis 

1 mi. S. of Annapolis 

Inverness to Monterey

Stewarts Point to Monterey

Pt. Reyes 

San Luis Obispo to Lompoc 

Lompoc 

San Vicente5

Santa Cruz Island 

Santa Cruz Island

Santa Rosa Island

By 2 n α-p ß-p- car sab terp 

----------------------------------------percent 4

---------------------------

F 17 95 - 98 0 0 0 0 

M 38 91 - 99 0 0 0 - 40 - 1 

M 10 2 - 98 0 0 - 84 0 - 4 0 - 10 

M 3 4 - 6 0 79 - 84 2 - 3 2 - 8 

F 14 1 - 12 0 74 - 88 0 7 - 10 

M 32 1 - 20 0 86 - 95 0 - 1 0 - 7 

S 106 2 - 36 * 57 - 88 0 5 - 8 

F 20 3 - 14 0 1 - 2 50 - 73 18 - 43 

M 20 4 - 13 0 1 - 2 44 - 74 8 - 31 

M n5 6 - 9 2 - 3 0 41 - 62 3 - 31 

F 7 23 - 32 0 1 - 2 32 - 38 27 - 40 

M 10 12 - 55 2 - 14 0 - 1 25 - 62 4 - 33 

M 15 12 - 60 2 - 20 0 - 1 9 - 62 9 - 12 

1 Locality of stand in California or source of seed in California when grown in New Zealand and reported by Forde (1964). 

2 Reported by: F = M. Forde; M = Mirov and others; S = Smith. 

3 α-pinene, ß-pinene, 3-carene, sabinene, terpinolene; most studies also report small to trace amounts of camphene, myrcene, limonene 

ß-phellandrene γ-terpinene and α-thujene. 

4 Normalized; * = trace. 

5 Baja California, number of trees not given; also reported for this locality was 4 percent myrcene, 10 percent limonene, 15 percent ßphellandrene. 

Table 3-41—Intervals of the frequency distribution of individual monoterpenes of P. muricata that 

were used to define the low (0), medium (1), and high (2) modes for a-pinene and 3-carene 

Monoterpene 

Code value α-Pinene 3-Carene 

---------------intervals in percent 1

--------------

(0) 0 - 6 0 - 24 

(1) 7 - 14 75 - 82 

(2) 15 - 100 83 - 100 

1

 Normalized. 

102 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-30—Frequency distribution of the amount of the listed 

xylem monoterpenes in 106 P. muricata in one stand at Pt. Reyes, 

California; each dot is measurement 

of one tree except where indicates each represents n trees; ▲ is 

average of set. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 103 
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Chapter 3 19 Pine Species of California Smith 

Table 3-42—The six coded types of composition in a stand of P. muricata at Pt. Reyes California their frequency in 106 trees, and their actual average composition; see table 3-41 for mode definition 

Actual composition 2 

Code 1 Value Frequency 

in 106 trees 

α-p 3-car myr ß-ph γ-ter terp 

--------------------------- -----percent 3

------------------

02 42 3 86 3 1 1 8 

11 27 10 79 2 1 * 7 

20 20 21 69 2 1 1 7 

12 4 7 83 2 0 0 7 

21 4 17 74 2 0 0 7 

01 3 6 82 2 1 1 7 

1

 Respectively: α-pinene, 3 carene; see table 3-41 for monoterpene values. 

2 α-pinene, 3-carene, myrcene, ß-phellandrene, γ-terpinene, terpinolene. 

3

 Normalized; * = trace. 

Table 3-43—Xylem monoterpene composition of 10 intraspecific hybrids of P. muricata growing in the arboretum at the Institute of Forest Genetics (IFG) 

Monoterpene 2 

Source 1 α-p cam ß-p car sab myr lim ß-ph oci ter 

----------------------------------------------------------------percent 3 

In x Fr 41.0 0.4 1.6 49.4 - 1.8 0.4 0.7 0.2 4.3 

In x Fr 47.7 0.3 1.2 42.8 - 1.7 0.4 0.8 0.2 4.3 

In x Fr 38.0 0.3 1.2 52.0 - 1.9 0.4 0.6 0.4 5.2 

Mon x Fr 93.4 0.7 2.9 - - 1.0 0.8 1.1 - -

Mon x Fr 95.6 0.7 1.7 - - 0.9 0.5 0.4 - -

Mon x Fr 97.1 0.7 0.9 - - 0.8 0.4 0.1 - -

SV x In 53.6 0.4 1.7 38.4 - 1.5 0.4 0.7 0.2 3.2 

SV x Mon 29.8 0.4 2.3 59.2 - 1.6 0.5 0.8 0.1 5.1 

SV x Mon 2.9 0.2 0.3 83.6 - 2.4 0.5 0.6 0.7 9.0 

SV x Lom 8.9 0.1 1.5 - 53.3 2.6 1.4 1.6 1.0 29.5 

1

 In: Inverness (middle type), Fr: Fort Ross (northern type), Mon: Monterey (middle type), SV: San Vicente (southern type), Lompoc 

(southern type). 

2 α-pinene, camphene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, ocimene, terpinolene. 

3

 Normalized; - =zero. 

104 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-31—Distribution of Pinus ponderosa, as taken from Critchfield and Little 

(1966). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 105 
Chapter 3 

19 Pine Species of California Smith 

genetics are covered by Wang (1977) and Conkle and Critchfield (1987). The 

latter is strongly focused on genetic variation and the relationship of P. ponderosa 

to other pines. 

Additional information on P. ponderosa xylem monoterpenes is given later 

in this volume on half-sibling populations (Chapter 5), on full-sibling 

populations (Chapter 6), on grafts (Chapter 7), on procedural measurements 

(Chapter 8) and on bioassay of resistance to attack of western pine beetle 

(Chapter 9). Included in Chapter 8 are several studies that showed little or no 

difference in composition of samples taken from various horizontal locations 

and over long intervals of time. There was a very small but consistent shift in 

composition from top to bottom of a mature tree: α-pinene and ß-pinene 

decrease, and myrcene and limonene increase. 

Traditionally, P. ponderosa has been divided into three varieties: var. 

ponderosa in the far West, var. scopulorum Engelm. in the northern and central 

Rocky Mountains and var. arizonica (Engelm.) Shaw in the southern Rockies 

(Wang 1977). Weidman (1939) proposed a different classification on the basis of 

climate. More recently, two classifications have been proposed on the basis of 

early growth characteristics (Squillace and Silen 1962; Wells 1964). All four 

classifications—traditional, climate, and two based on early growth—differ 

noticeably. One of the more variable characteristics of P. ponderosa—among 

many variable ones—is xylem monoterpenes. Mirov (1961) found strong 

evidence for regional differences by examining trees growing at the Institute of 

Forest Genetics (IFG) from seed collected throughout the range of the tree; 

there were large regional differences in α-pinene, ß-pinene, and 3-carene. But 

Mirov's sampling was insufficient to define regional types. Smith (1964a) also 

found considerable variation in α-pinene, ß-pinene, 3-carene, and limonene 

among local populations in Eldorado County, California. Smith and others 

(1969) examined a large number of trees growing at IFG from seed collected 

throughout the range and made the first attempt to define regional variation on 

the basis of average composition. Smith (1964a, 1964b, 1966c, 1968) found 

within-tree composition to be quite constant. Three studies have been made 

which describe parts or all of the regional variation. (1) Peloquin (1964) 

examined trees in southwestern Arizona and concluded that there is great 

variation and that there was strong evidence of hybridization between P. ponderosa and P. engelmannii. (2) Sturgeon (1979) examined a series of stands in 

northern California and southern Oregon, and the results solidify that part of 

the regional classification of P. ponderosa and also suggest some degree of 

relationship between the resin composition of the stand and the severity of 

depredation by western pine beetle. (3) Smith (1977) made a range-wide study 

with 65 stands of about 75 trees per stand and described five regional and four 

transitional ecotypes on the basis of stand averages (fig. 3-32). When the average 

stand values for the five major monoterpenes in each stand were mapped, they 

fell into natural groupings which suggest regional types of stands. All stands 

that differed significantly from each other by no more than one of the five major 

components were placed in the same region (Smith 1977). Stands differing by 

two or more components were placed in other regions. Five regions were 

defined by this procedure. Each of the five regions differed significantly from 

each other in at least two of the components, and often in all five. There were 

other stands outside of these regions that differed significantly from each other 

in two to five components and from the adjoining regions in four or five 

components; these were grouped geographically into transition zones. Thus, 

stands within a region were quite similar to each other, while stands in zones 

were neither strongly similar to each other nor to the stands in the adjoining 

regions. 

A classification based on the whole composition of a tree was also proposed 

(Smith 1977) in which the monoterpene composition of each tree was coded on 

106 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-32—Regions and zones of P. ponderosa xylem monoterpene ecotypes in western United States based on correlation of 

frequency of occurrence of tree types of monoterpene composition in 65 stands, superimposed on the tree's distribution from 

Critchfield and Little (1966). Regions are: I, San Jacinto; II, Sierra 

Pacific; III, Cascade Northern; IV, Mogollon West; V Mogollon East; Vl, 

Coronado. Zones are: A, Tehachapi; B, Escalante North; C, Cedar 

Breaks; D, Escalante South. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 107 
Chapter 3 

19 Pine Species of California Smith 

the basis of modalities in the frequency distribution of each of the five major 

monoterpenes, enabling the composition of each tree to be expressed as a 

discrete five-digit number. This is called the coding procedure. Thus five 

variates, the five major components, were expressed as a single variate, the 

coded composition of the tree. Accordingly, each stand could then be 

characterized by the number of trees of each type of composition, and the 

distribution of the frequency of the types of composition conformed generally 

to the region and zone classification established by average monoterpene 

composition noted above, but there were some differences. At that time, 

however, no analysis was made of the frequency of these tree types by stands, 

nor was an analysis made of the intraregional structure other than that done on 

the basis of average composition. Coding provides a procedure for analyzing 

all major components simultaneously rather than on the basis of individual 

components one at a time or sequentially. Such a system should be superior to 

the analysis of stand averages in determining the overall regional structure and 

the uniformity or variation within regions. A multivariate procedure, such as 

the one used, would also be of value when an interrelationship between 

components is suspected. 

A Regional Classification 

The coding of 4,894 trees, using the coding criteria (table 3-44), defined 112 

composition types. The 60 most common types comprised 97 percent of the 

trees in the study (table 3-45). These 60 types were used to determine the 

frequency of each type in each of the 65 stands; frequency was normalized to 

give the percentage of each type in the stand. Because nearly all stands had 70 

to 80 trees, the normalized value of occurrence of coded types and the actual 

numbers of types of composition were quite similar. Early in the study, a 100-

tree stand was considered, but the logistics of the field work would not 

accommodate such sampling, and an 80-tree stand was selected. In this Chapter 

the phrase "frequencies of tree types" refers to the normalized frequencies, i.e., 

to percentages. 

The association between stands was calculated by using the frequencies of 

tree types in each stand as the variable. These were called coefficients of 

association and were used as a measure of the similarity in the distributions of 

types of trees in the various stands. The coefficients calculated in this manner 

were strongly influenced by the most frequent tree types. Any two stands in 

which the distribution of the most frequent types of trees was quite similar 

tended to be strongly correlated even if the distributions of the less frequent 

compositions were somewhat different. Hence, when an association was used 

to classify stands into regions, the classification method was such that stands 

with similar frequencies of the most common types of trees were usually 

classified together. This approach, therefore, provides some measure of 

magnitude, similarity, or association. A chi square value was calculated for all 

stand pairings. When the association was negative between two stands, the 

coefficient was simply designated as a negative and the association between 

the two stands was simply given a minus category without a numerical value. 

Stands were geographically arrayed—using the classification proposed 

earlier (Smith 1977) as a guide—according to the strength of association, by the 

pattern of occurrence of types of composition, and by the association of each 

grouping with other groupings (table 3-46). Thus, some degree of flexibility had 

to be applied in determining regions and zones. When all 65 stands were 

aligned according to the value of association for all pairings, a structure was 

established (fig. 3-32), composed of six regions and four transition zones; this 

resembled, to some degree, the classification originally proposed (Smith 1977). 

This structure showed the average association between the stands of each of six 

groupings to be about 0.8 to 0.9 (table 3-46); these were called regions: (I) San 

Jacinto, (II) Sierra Pacific, (III) Cascade Northern, (IV) Mogollon West, (V) 

108 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Table 3-14—Intervals in the frequency distribution of individual monoterpenes of P. ponderosa 

that were used to define the low (0), medium (1), and high (2) modes for the five noted monoterpenes 

Code Value 

Monoterpene 0 1 2 

-------------------------------- intervals in percent1 --------------------------------

α-Pinene 0 -17.4 17.5 - 64.4 64.5 - 00 

ß-Pinene 0 - 4.4 4.5 - 35.4 35.5 -100 

3-Carene 0 -15.4 15.5 - 35.4 35.5 -100 

Myrcene 0 - 2.4 2.5 - 15.4 15.5 -100 

Limonene 0 - 2.4 2.5 - 17.4 17.5 -100 

1 Normalized. 

Table 3-45—The 60 most common composition types of P. ponderosa xylem resin: A = the numerical listing of the 60 types; B = coded type designation; the five numbers under B are respectively from left to 

right a-pinene, b-pinene, 3-carene, myrcene, limonene, each of the five values tinder C are average actual composition of the trees of coded type listed in column B and in the same order

1

; N = numerical occurrence 

of each type in 4,731 trees classified. See figure 3-33 for the distribution of the pipes in each region and zone. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 109 
Chapter 3 

19 Pine Species of California Smith 

Mogollon East, and (VI) Coronado. The average association for the two other 

groupings was only 0.6 to 0.7; these were called transition zones: (B) Escalante 

North, and (D) Escalante South. Two stands, #30 and #46, could not be clearly 

aligned with any of the groups. These two were also called transition zones— 

(A) Tehachapi and (C) Cedar Breaks. Thus, by strength of coefficients-of-association grouping, six regions and four transition zones of ponderosa pine 

monoterpene ecotypes were established. The term "transition zone" was used 

for an area between regions, or other zones, where nearby stands were not 

strongly associated and where composition types resembled, somewhat, those 

of the regions and zones around the zone. 

It was clear that all groupings differed from each other in either the 

incidence or frequency of several types of composition (fig. 3-33). Increasing the 

number of sample trees in a region or zone may increase the total number of 

types of composition in that region or zone; but the number of types in a 75-tree 

stand did not increase. 

The following is a discussion of each region and zone and its association 

with other regions and zones (table 3-46 and figs. 3-32 and 3-33). The order of 

presenting the regions and zones was a clockwise route from southern 

California northward to the Canadian border, then eastward to the Rockies, 

and then southward through the Rockies and Great Basin to southern Arizona. 

A similar transect gave the frequency distribution of the five major 

components—α-pinene, ß-pinene, 3-carene, myrcene, limonene—in a 

representative stand from each region and zone (fig. 3-34). The average 

coefficient of association and the range will be given for each set of comparisons. 

This is shortened in the following discussion to "association." 

Region I, San Jacinto, had four stands and had an average internal association 

for the four stands of 0.89 ranging from 0.87 to 0.97. San Jacinto was associated 

positively with Tehachapi, the coefficient of association averaging 0.54 and 

ranging from 0.49 to 0.57; and with Sierra Pacific averaging .05 and ranging 

negative to 0.17. San Jacinto was associated negatively with all other regions 

and zones. The most common type of composition, #1, was also found in 

Tehachapi, Sierra Pacific, and Escalante North. 

Transition Zone A, Tehachapi, had only one stand and was given a 

hypothetical internal association of 1.00. It was associated positively with three 

regions: San Jacinto, as noted above; Sierra Pacific with an average association 

of 0.71 and ranging from 0.51 to 0.81; Cascade Northern with an average 

association of 0.26 and ranging from 0.10 to 0.44. Tehachapi was also associated positively with two transition zones: Ecalante North with an average association 

of 0.36 and ranging from 0.25 and 0.50 and Cedar Breaks with an average of 0.03 

and without a range of values because both were single stand zone associations. 

Tehachapi was associated negatively with all other regions and zones. 

Tehachapi had six fairly abundant coded types, three of which were common 

types in San Jacinto while three were common types in Sierra Pacific. 

Region II, Sierra Pacific, had 14 stands with internal association of 0.88 

ranging from 0.66 to 0.97. Sierra Pacific was associated positively with San 

Jacinto and Tehachapi as noted above. It was also positively associated with 

Cascade Northern, with an association of 0.44, ranging from 0.14 to 0.76; with 

the Escalante North with an average of 0.56 and ranging from 0.27 to 0.79; and 

with Cedar Breaks, with association of 0.11, ranging from 0.02 to 0.16. Sierra 

Pacific was negatively associated with all other regions and zones. The more 

common types of composition in Sierra Pacific were also commonly found in 

Tehachapi, Cascade Northern, and Escalante North. Some types common to 

Sierra Pacific and Escalante North were not common to Cascade Northern. 

Sturgeon (1979) suggested that the Sierra-Pacific region extended into the 

Siskiyou and Klamath Mountains of northern California, and into southern 

Oregon, west of the crest of the Cascades. 

110 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 111 
Smith 

Table 3-46—Coefficients of association, with decimal 

point removed, among 65 mature stands of P. ponderosa 

and the delineation of six regions ( I - VI) and four transition 

zones (A-D); stand numbers along right side are from Figure 3-31; 

0 equals zero, (-) equals minus value; triangular shaded areas 

delineate stands Within a region or zone, except for the two, single 

stands of the Tehachapi and Cedar Breaks transition zones which are 

fully outlined to show their association with all stands. 

Chapter 3 19 Pine Species of California 

112 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-34—Frequency distribution of the 

amount of the noted monoterpenes in a typical 

stand of P. ponderosa in each of the six regions and 

meas

four transition zones, listed on the right; each dot is 

urement of one tree, except where indicates 

each is n trees; ▲ is average of stand. 

(fig 3-34 continues on the next 4 pages). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 113 
Chapter 3 19 Pine Species of California Smith

114 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 115 
Chapter 3 19 Pine Species of California Smith

116 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 117 
Chapter 3 

19 Pine Species of California Smith 

Region III, Cascade Northern, had 19 stands with internal association of 0.88, 

ranging from 0.68 to 0.98. Cascade Northern was associated positively with 

Sierra Pacific and Tehachapi as noted above. It was also associated positively 

with Escalante North, with an association of 0.65, ranging from 0.16 to 0.95; 

and with Cedar Breaks, with of 0.23, ranging from 0.20 to 0.25. Cascade Northern was negatively associated with all other regions and zones. The 

frequency of types of composition in Cascade Northern showed how it was 

linked with both Sierra Pacific to the west and south and to Escalante North to 

the south. Using other characteristics of P. ponderosa, others have found a 

significant shift at the Missouri River in Montana. No such shift was found in 

this study using xylem monoterpenes. The shift found by others should have 

occurred between stands 58 and 60. Though Cascade Northern was the largest 

geographical area, there was surprisingly excellent association among widely 

separated plots (table 3-45). For example, the association between stand #65 in 

southern Colorado and stand #41 in northern California was 0.80 (table 3-46). 

Transition Zone B, Escalante North, had six stands, with an internal 

association of 0.63, ranging from 0.28 to 0.83. Escalante North was associated 

positively with Cascade Northern, Sierra Pacific, and Tehachapi as noted above. 

It was also associated positively with Cedar Breaks, with an average association 

of 0.32, ranging from 0.14 to 0.61; and with Mogollon West, with an association 

of 0.01, ranging from a negative association to 0.20. It was negatively associated 

with Escalante South, both Mogollon regions, and Coronado. 

Escalante North had a great range in types of composition, tending to link it 

with all regions and zones (fig. 3-33). The separation of Escalante North and 

Escalante South into two transition zones is clearly evident from the frequency 

of types of composition (fig.3-33), the characteristics of the frequency distribution 

of individual monoterpene components (fig. 3-34), and the differences in the 

coefficients of association with other regions and zones (table 3-46). 

Transition Zone C, Cedar Breaks, had only one stand and therefore had no 

internal association but has been given a hypothetical one of 1.00. Cedar Breaks 

was associated positively with Escalante North, Cascade Northern, Sierra 

Pacific, and Tehachapi as noted above. It was also associated positively with 

Escalante South, with an average association of 0.41, ranging from 0.05 to 0.50; 

with Mogollon West, with an average association of 0.60, ranging from 0.50 to 

0.69; and with Magollon East, with an average association of 0.26, ranging from 

0.18 to 0.35. Cedar Breaks was associated negatively with only two regions, 

Coronado and San Jacinto. It was tempting to place Cedar Breaks in either of 

the two Escalante zones. However, the occurrence of compositional types 

suggested that it should stand alone between the two zones. It would be 

interesting to see what types of composition would show up in a 200- to 300-

tree sample in Cedar Breaks. 

Transition Zone D, Escalante South, had five stands, with an internal 

association of 0.56, ranging from 0.22 to 0.84. Escalante South was associated positively with Cedar Breaks as noted above. It was also associated positively 

with Mogollon West, with an association of 0.57, ranging from 0.12 to 0.83; with 

Mogollon East, with an association of 0.43, ranging from .00 to 0.74; and with 

Coronado, with an association of 0.02, ranging from a negative association to 

0.21. It was negatively associated with all other regions and zones. 

The two Escalante zones and Cedar Breaks were the most interesting 

geographical areas of P. ponderosa because in aggregate, they had just about 

every type of composition found in P. ponderosa in a sample of only a little more 

than 800 trees. There is little doubt that more work should be done in this area, 

particularly in studies of large stands of several hundred trees each. 

Region IV, Mogollon West had seven stands, with an internal association 

averaging 0.79 and ranging from 0.65 to 0.97. Mogollon West was associated 

118 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
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th 19 Pine Species of California Chapter 3 

positively with Escalante South and Cedar Breaks as noted above. It was also 

associated positively with Mogollon East, with an association of 0.62, ranging 

from 0.38 to 0.78; and with Coronado, with an association of 0.05, ranging from 

a negative association to 0.25. It was associated negatively with all other 

regions and zones. 

Region V, Mogollon East, had five stands, with an internal association 

averaging 0.87, and ranging from 0.72 to 0.94. Mogollon East was associated positively with Mogollon West, Escalante South, and Cedar Breaks as noted 

above. It was also associated positively with Coronado, with an association of 

0.11, ranging from a negative association to 0.32. It was associated negatively 

with all other regions and zones. 

The two Mogollon regions were the weakest regions with internal 

association of about 0.80. Yet they were associated with each other, with an 

association of only 0.6, and they differed markedly in the level with which they 

were associated with other regions and zone (table 3-47). They had much the 

same types of composition but differed in the frequencies (fig. 3-33). 

Region VI, Coronado, had three stands, with an internal association averaging 

0.9 and ranging from 0.86 to 0.94. It was associated positively with Mogollon 

East, Mogollon West, and Escalante South as noted above. It was associated 

negatively with all other regions and zones. It was clear that this region stands 

alone on the strength of a high percentage of 20000 coded types, i.e., nearpure α-pinene, but this same type of tree can be found in the two Mogollon 

regions and the Escalante South zone. Peloquin (1984) proposed an elevational 

transition zone between the Coronado region and Mogollon east region with the 

Mogollon region at the higher elevation. 

In summary, each of the six regions had very strong internal coefficients of 

association of 0.8 to 0.9 between stands within that region, but the associations 

between stands of two different regions were, at best, 0.5 to 0.7, and many were 

negative. The two Mogollon regions were the weakest regions, with internal 

associations of about 0.8. However, if one were to combine the two Mogollon 

regions into one region, the internal association would drop to 0.7. Thus, though one might choose to combine the two Mogollon regions into a single, 

large region, I have chosen the two-region structure because the single large 

region would have too low an internal integrity. The difference between regions 

and zones was also clearly evident in the configuration of the frequency 

distribution of the individual monoterpenes in a typical stand of about 80 trees 

for each region and zone (fig. 3-34). 

Two of the transition zones, Tehachapi and Cedar Breaks, had only one 

stand each. Therefore, they had no internal value for range and were given a 

hypothetical internal value for association of 1.00. The weakest groups were the 

Escalante North and South transition zones. One might be tempted to add them 

to adjoining regions and zones or to make one large transition zone. However, 

to do so would weaken the internal strength of the zones and would change the 

associations with other regions and zones. Given the present data, this 

assignment appears the most appropriate. 

The structure based on the total composition of the tree as a single unit 

should be the strongest (figs. 3-32 and 3-33, table 3-46). 

All regions had three to five characteristic types of monoterpene 

composition that were usually found less commonly in adjacent regions or 

zones (fig. 3-33). The four transition zones tended not to have their own 

characteristic types; instead, they usually had several types which were often 

more common in other, usually adjacent, regions or zones. In general, a strong 

association between stands was largely dependent on the high frequency of 

three to five common types of trees, and weakly dependent on the low 

frequency of 10 to 20 other types. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 119 
Chapter 3 

19 Pine Species of California Smith 

Four of the regions with an internal average association of 0.9 were quite 

different in the nature and extent of the distribution of P. ponderosa: San Jacinto, 

Sierra Pacific, Cascade Northern, and Coronado. Sierra Pacific and Cascade Northern extend over very great distances (600 to 1,500 miles). These regions 

were characterized by much greater continuity of stands, though within each 

there are isolated stands. Both Coronado and San Jacinto are geographically 

small regions, with a maximum extent of less than 150 miles. Both were also 

somewhat similar in having small stands with discontinuous distribution. This 

suggested that stands may have been more continuous in the recent past, and 

since then have become more isolated. 

The Cedar Breaks zone occupied a singular and pivotal position in this 

geographic structure of P. ponderosa. It was associated positively with all regions 

and zones except San Jacinto and Coronado. Additionally, all regions and 

zones listed before it (I, II, III, A, B) had no positive associations with those 

listed after it (IV, V, VI, D). 

Differences between all regions and zones were also clearly evident from 

the frequency distribution of the five major monoterpenes in a typical stand in 

each region and zone (fig. 3-34). 

Though the areas classified as regions were fairly homogeneous, with very 

high internal correlations, they possess the capacity for very large shifts in 

monoterpene structure as shown by the wide range of monoterpene types in a 

given stand and by the large frequency distributions of several components. 

One would wonder about the forces which produce such stability and 

uniformity in the face of such a potential for differentiation. Stands in two of 

the regions may be an indication of possibilities that may be underway. Stand 

35, located in the North Coast range of California of the Sierra Pacific region, 

has an association of 0.7 with three other stands in the region. This was much 

lower than other stands in the region. Is P. ponderosa in the coastal mountains 

beginning to differentiate from the rest of the region? Stand 55, located in the 

northern part of the Cascade Northern region, had an association of 0.7 or 0.6 

with 10 other stands in the region; this was a much greater difference than any 

other stand. Is this an indication that another region of P. ponderosa extends 

northward into Canada? However, the sharp lines of division of the mode 

classification procedure plus small environmental effects on monoterpene 

composition could cause a slight shift in the classification of the type of some 

trees, causing an occasional stand to be less strongly associated with the other 

stands in the region. Stand size of 80 trees was expected to reduce the incidence 

of such inconsistencies. 

Further study is needed in the northern end of the Sierra Pacific region and 

the northern end of the Coronado region to see if there is elevational transition 

with adjoining regions. 

The two single-stand zones, Tehachapi and Cedar Breaks, appeared to offer 

the best opportunities for further study. Both areas were small and moderately to poorly associated with several regions or zones. The aggregate of the two 

Escalante zones also appeared to offer excellent opportunities for further study, 

but they were much more extensive than the two one-stand zones. The Escalante 

zones also presented the most difficulty in placement of stands, and their 

location could be modified by more intensive study of additional and larger 

stands. The distribution of P. ponderosa in the two Escalante zones tended to be more disjunct than in other areas. 

Neither of the two classifications based on monoterpenes (Smith 1977), or 

as given in this volume, closely resembled those derived by other criteria. 

These criteria included the traditional three varietal classifications based 

primarily on morphology and geography (Wang 1977), that based on climate 

(Weidman 1939), or those based on early growth characteristics (Wells 1964) 

120 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
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th 19 Pine Species of California Chapter 3 

(Squillace and Silen 1962). For example, the area assigned to traditional var. 

ponderosa included all or part of three regions and one transition monoterpene 

ecotype: San Jacinto, Sierra Pacific and Cascade Northern regions, and the 

Tehachapi transition zone. The agreement of monoterpene ecotypes with the 

other varietal classifications of P. ponderosa was equally as poor as with the 

traditional classification. 

Conkle and Critchfield (1987) used all available criteria in describing the 

distribution of P. ponderosa. Adjustments were made in the basic three-variety 

structure to incorporate studies of mature morphology, seed and seedling 

characteristics, xylem resin, and cone color, as well as long-term intraspecific 

breeding studies. 

Adjustments made in this report to the original classification did not change 

the conclusion in the earlier report that the distribution of certain species of Dendroctonus follows the ecotypes of this classification. Of particular note is that the northern limits of distribution of D. adjunctus Bland. falls in Escalante 

transition zones. 

One of the objectives of the work with P. ponderosa was to locate trees high 

in limonene for study and breeding because early research showed that 

limonene reduced the success of western pine beetle attack. Four locations were 

found (table 3-48): Ranger Peak on Los Padres National Forest, Adin Summit and 

Blue Lake on Modoc National Forest, and Wheeler Peak on Humboldt National 

Forest (now part of the Great Basin National Park). The breeding work done with 

these trees is covered in Chapter 6. Their generalized formula was 20 percent α­

pinene, 0 percent ß-pinene, 0 percent 3-carene, 20 percent myrcene, and 60 

percent limonene. The four areas do have similarities: (a) modest to high amount 

of limonene; (b) trees without ß-pinene; and (c) trees without 3-carene. The few 

stands with high limonene had similar averages for limonene, but they differed 

enough in types of composition to be in different regions or zones. 

Local Variation 

In 1970, after finding the first high-limonene tree as discussed in the previous section, a 

study was made at Adin Summit (fig. 3-31, stand #40) to see if there were more highlimonene trees there, that could be used for breeding and bioassay research, and to 

determine the variation among five stands of differing size and location in that area. 

Five stands were used for the study as follows: 

1. The original stand #40: 78 trees; 

2. A surrounding large stand: 366 trees; 

3. A large stand about 1 mile west: 377 trees; 

4. A large stand about 3 miles southwest: 641 trees; 

5. A standard stand about 15 miles north: 94 trees. 

The composition of all trees was coded according to specifications (table 3-44) 

the frequency of types of composition in each stand was determined (fig. 3-35), 

and stands were compared by coefficients of association. 

Though the stands were quite similar, their coefficient of association were 

generally about 0.6 rather than the 0.7 to 0.8 that one would expect for stands in 

the Sierra Pacific region—the region in which the stands were located. However, 

the basic stand at Adin Summit may be right at the beginning of a transitional 

zone between the Sierra Pacific region and the Cascade Northern region. No 

such zone was found or reported earlier in this section. But somewhere in this 

general geographic area one might expect to find such a zone. Stand 5, located 

about 15 miles north of Adin Summit, had the poorest coefficients of association. 

This suggested that Stand #5 was approaching the Cascade Northern region. It 

would be possible to establish a transition zone about 15 miles north of Adin 

Summit, near stand #5. There are stands of P. ponderosa throughout the area, USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 121 
Chapter 3 19 Pine Species of California Smith 

Table 3-47—Average coefficient of association between Mogollon East and Mogollon West regions of P. ponderosa and associated regions and zones; bracketed ( ), values are average internal values for the stands within 

each of the two regions 

Region 

Region or zone Mogollon East Mogollon West 

Coronado 0.11 0.02 

Mogollon East (0.87) 0.62 

Mogollon West 0.62 (0.79) 

Escalante South 0.43 0.57 

Cedar Breaks 0.26 0.60 

Escalante North negative 0.01 

Table 3-48—Average xylem monoterpene composition in four stands of P. ponderosa and of the composition 

of individual trees in them classed as high limonene, and the percent terpene in whole resin 

Stand 1 Trees Monoterpene 2 Terpene in 

number dbh sampled whole resin 

α-p ß-p car myr lim ter 

inches number -------------------------------- percent 3 ----------------------------- percent 

40 - 78 6.2 20.4 44.3 13.8 11.8 2.6 25 

26 14 17.6 0.7 0 22.1 58.1 0 26 

7 15 21.7 3.2 0 18.3 56.8 0 -

9 15

 20.8 23.1 0 12.0 42.9 0 23 

28 15

 14.5 18.8 0 21.3 45.3 0 22 

42 - 79 11.9 20.9 38.4 8.4 14.9 2.1 26 

17 1 25.6 0.4 0 16.1 57.9 0 22 

14 1 24.3 0.4 0.1 18.1 56.9 0 22 

30A - 36 6.0 29.0 25.1 18.0 21.0 1.0 24 

15 1 11.6 3.0 0.2 14.9 70.3 0 24 

BL - 40 8.8 21.7 44.8 11.6 9.8 2.7 -

30 1 6.5 11.7 0 27.4 54.6 0 -

1 See figure 3-31 for location of stands. 

2 α-pinene, ß-pinene, 3-carene, myrcene, limonene, terpinolene. 

3 Normalized, minor components comprise the remainder of 100 percent. 

4 Found in original 78-tree stand. 

5 Found when stand was enlarged to about 1600 trees. 

122 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-35—Normalized distribution of composition types of P. ponderosa xylem monoterpenes in five stands of different sizes near Adin 

Summit, Modoc National Forest; see table 3-45 for 

actual composition of coded types. Occurrence is 

normalized for each stand. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 123 
Chapter 3 19 Pine Species of California Smith 

and it would interesting to sample a series of stands running northeast of Adin 

Summit into southern Oregon. 

One other small study is of note here in addition to what is given in Chapter 

8. An elevational transect was made in the Central Sierra Nevada to see if there 

is any effect of elevation on composition. Twelve small stands of 10 to 20 trees 

each were sampled between Placerville and Lake Tahoe from 1800 feet elevation 

to 6500 feet, and a 181-tree stand at 3800 feet, about mid-elevation, was sampled 

for comparison. Although there was considerable local variation among the 

trees of a given stand, there was essentially little or no difference in average 

composition over the complete range of elevation. The following was the 

average percent composition, minor components omitted, for the extremes in 

elevation; N is number of trees: 

Elevation N α-pinene ß-pinene 3-carene myrcene limonene 

ft -------------------------------------percent ---------------------------

1800 19 7 26 41 12 12 

6500 13 6 25 39 14 13 

all 163 6 29 36 10 14 

3800 181 7 28 33 12 17 

#15. Pinus quadrifolia Parl. (Parry pine)

P. quadrifolia is found in a few scattered stands in San Diego, Imperial, and 

Riverside Counties in southern California. However, the major portion of its 

range is in northern Baja California, Mexico, at lower elevations in the San

Pedro Martir Mountains (fig. 3-36). It is another pinyon pine and grows on dry

sites, much like P. monophylla and P. edulis. 

Mirov (1961) analyzed the resin of trees in Riverside County and found the 

monoterpene composition to be nearly-pure α-pinene; there was also a 

substantial amount of sesquiterpene. 

Zavarin and others (1980) looked more extensively and concurred with 

Mirov that the monoterpene composition was near-pure α-pinene. Zavarin and 

others (1980) also found small to trace amounts of tricyclene, camphene, ßpinene, 3-carene, limonene, myrcene, ß-phellandrene, terpinolene, γ-terpinene, 

ocimene, and p-cymene. 

Zavarin and others (1980) studied the possible introgression of P. quadrifolia 

and P. monophylla to get additional data on variation of Parry pine. They found 

little or no variation throughout the range (table 3-49); the average amount of αpinene was essentially 94 percent in all stands with the S.D. ranging from only 

2.1 to 2.6. No other monoterpene averaged more than 3 percent; most averaged 

less than 1 percent. Zavarin and others (1980) also found a stand with 

monoterpene composition and morphological characteristics suggestive of 

introgression between P. quadrifolia and P. monophylla. It would seem that 

monoterpene evidence of introgression would have to be found in the minor 

components because both species—P. quadrifolia and P. monophylla—were very 

high in α-pinene. The average α-pinene for P. quadrifolia was greater than 90 

percent while the average for P. monophylla was slightly more than 80 percent. 

But many individual trees of P. monophylla had more than 90 percent α-pinene. 

Thus, one might be inclined to separate the two pines as species on the basis of 

α-pinene because they were somewhat different. Many P. monophylla trees can 

have appreciable amounts of limonene, 3-carene, myrcene, ß-phellandrene, 

and ocimene; these might be useful in separating the two species. 

124 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
------------------------------------- 

Smith 19 Pine Species of California Chapter 3 

Figure 3-36—Distribution of P. quadrifolia in southern California, taken from 

Little and Critchfield (1966). 

Table 3-49— Average xylem monoterpene composition of four natural stands of P. quadrifolia adapted from Zavarin and others (1980) and of 

one plantation stand at IFG; n = number of trees in the sample 

Monoterpene Stand location component 

California Baja California 

Laguna Mtns Rumorosa Pine Solo Mikes Peak IFG1 

------------------------------------------------------percent2 

Tricyclene * * * 

α-Pinene 94.9 93.2 94.9 

Camphene 1.1 1.3 0.7 

ß-Pinene 0.7 0.4 0.4 

3-Carene 0.3 0.2 * 

Myrcene 0.8 0.7 1.1 

Limonene 0.9 2.7 1.5 

ß-Phellandrene 0.1 * * 

γ-Terpinene - 0.1 * 

Ocimene 1.0 0.8 0.5 

p-Cymene 0.1 0.1 0.3 

Terpinolene 0.2 0.5 0.1 

n 20 10 10 

* -

94.0 84.7 

1.1 0.4 

0.6 0.8 

0.1 1.6 

1.2 4.1 

1.8 0.9 

* 2.2 

0.2 * 

0.5 5.3 

0.5 -

0.1 0.9 

10 6 

1

From seed collected in San Diego Co.; also had a trace of sabinene. 2

Normalized; * = trace, - = zero. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 125 
Chapter 3 19 Pine Species of California Smith 

Six trees growing at the Institute of Forest Genetics (IFG) from seed collected 

in San Diego County (table 3-50) were much lower in α-pinene than reported by 

Zavarin; some of these individual trees had much greater 3-carene (9.3 percent), 

ocimene (6.5 percent), and myrcene (6.6 percent) than had been previously 

reported for P. quadrifolia. Although the differences between the set of 10 trees 

grown at IFG and the four sets reported by Zavarin and others (1980) were 

small, they were consistent enough to suggest an environmental effect. Both 

myrcene and ß-phellandrene were different in the two sets. These two 

components have been suspected of responding to environmental factors in 

other instances. One might conclude that all P. quadrifolia have a (1-1) set of 

alleles for α-pinene and that all other monoterpenes were derived from 

isomerization or biosynthetic by-products. Therefore, if introgression with P. 

monophylla was evidenced by the minor monoterpenes that appear to be 

nongenetic, one would have to assume that isomerization of monoterpenes was 

under some type of inherited control, or was related to the basic composition 

that is under strong genetic control. 

Little or no difference in composition was found between a basal tree 

sample and one at 20 feet (see table 8-1). 

#16. Pinus radiata D. Don (Monterey pine) 

The natural range of P. radiata is limited to three clearly separated localities 

along the coast of California (fig. 3-37). P. radiata has been widely planted in 

California and around the world, particularly in Australia, Chile, South Africa, 

and New Zealand. As noted earlier, P. radiata and P. attenuata were extensively 

used in pine hybridization research from about 1940 to 1960 at the Institute of 

Forest Genetics (IFG) at Placerville. There is some uncertainty about the varietal 

status of P. radiata in Baja California. Griffin and Critchfield (1972) mentioned it 

but did not include it in the distribution. Millar (1986) gave varietal status to the 

species in Baja California, in fact claiming that it consisted of two varieties. I am 

following Griffin and Critchfield and will not include the southern island 

varieties; also, there were no terpene data on the island varieties. 

Mirov (1961) reported four early results of studies of the xylem 

monoterpene composition to be various combinations of α-pinene (α-ρ) and ßpinene (ß-ρ) as follows: 

Study α-ρ ß-ρ Reported by Location of trees 

---- percent ------

1 34 64 Barrud none given 

2 24 75 McCombs New Zealand 

3 41 56 Arbuzou Russia 

4 75 22 Mirov IFG 

None of these reports showed any significant amount of monoterpenes 

other than α-pinene and ß-pinene, but the range in these two components 

was large. 

The first detailed study by gas chromatography was by Bannister and 

others (1962) who sampled five populations: the three natural populations in 

California and two plantation populations in New Zealand. Size of sample 

ranged from 27 to 53 trees. Their results showed α-pinene varying from about 

20 to 50 percent and ß-pinene varying from about 42 to 80 percent, with the 

amounts nearly complements. They also reported trace amounts of camphene, 

limonene and ß-phellandrene. Though no individual tree data were given, 

their diagram of the relationship of α-pinene and ß-pinene suggested a trimodal 

126 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Table 3-50—Xylem monoterpene composition of six trees of P. quadrifolia grown in an arboretum at the 

Institute of Forest Genetics (IFG) from seed collected in San Diego Counts, 

No. Monoterpene 1 

α-p cam ß-p car sab myr lim ß-ph oci ter 

--------------------------------------------------- percent 2 -----------------------------------------------------

1 76.7 0.4 0.6 9.3 - 3.1 0.5 0.1 6.2 2.6 

2 86.8 0.3 0.6 - - 6.6 - - 5.0 0.4 

3 81.3 0.4 0.9 - 0.6 3.9 2.6 4.4 5.5 0.3 

4 88.1 0.5 0.8 - - 1.9 0.4 0.9 6.2 1.2 

5a 3 90.8 0.4 1.1 - - 2.3 0.5 2.0 2.2 0.5 

5b 88.1 0.4 1.0 - - 2.8 0.8 1.3 5.5 0.1 

6a 84.6 0.5 0.6 - - 6.5 0.7 - 6.5 0.6 

6b 86.8 0.5 0.6 - - 5.9 0.5 - 5.5 0.2 

1 α-pinene, camphene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, ocimene, 

terpinolene. 

2 Normalized; - = zero. 

3 a and b are samples of the same tree taken 5 years apart. 

Figure 3-37—The natural distribution of P. 

radiata in California, taken from Critchfield 

and Little (1966); stands on islands off the 

coast of Baja California are not included. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 127 
C

hapter 3 19 Pine Species of California Smith 

distribution of the two components (Bannister and others 1962); the data 

suggested modes for α-pinene at 20 to 30 percent, 30 to 45 percent, and 45 to 60 

percent, with respective percentage ratios of 30:46:24 for the low, medium, and 

high modes. Low mode for ß-pinene was 40-55 percent, mid ß-pinene was 56-70 

percent, and high ß-pinene was 71-80 percent. Alpha-pinene was the 

complement of ß-pinene. Bannister and others (1962) in one of the early studies 

of within-tree variation, showed no change in composition with time and 

within-tree position. Likewise, I could find little or no difference in composition 

between a basal tree sample and one at 20 feet. On the basis of averages, there 

were no sharp differences among the three California sources. 

Forde (1964), in investigating the inheritance of P. radiata x P. attenuata 

hybrids, showed ß-pinene in 37 P. radiata to range from 25 to 50 percent; the 

distribution appeared to be a single mode. Forde concluded that P. radiata was 

heterozygous for monoterpenes. 

Another detailed study by Blight and others (1964) examined 240 trees in 

eight localities including the three natural stands in California and five plantations in New Zealand. They reported average stand values with a narrow 

23 to 35 percent α-pinene and 64 to 76 percent ß-pinene, with about 1 to 2 

percent minor components. No listing of individual trees nor the frequency 

distributions of individual components were given, but the small standard 

deviations could suggest that most of the individual trees were very close to 

the average. 

Valenzuela and others (1966) examined five trees planted in Chile. Their 

results differed somewhat from the previous report, showing much higher α­

pinene (38 percent), small amounts of limonene (4 percent) in some trees, and a 

significant amount of sabinene (6 percent) in three trees. Could they have been 

working with trees with some content of P. muricata? 

Strauss and Critchfield (1982) sampled 308 hybrids of P. radiata x P. attenuata 

(2-4 years old) for xylem monoterpenes and subjected the results to various 

statistical analyses. They concluded that ß-pinene— found in P. radiata but not 

in P. attenuata—was controlled by a single dominant gene. However, they had 

difficulty in discriminating between a single-gene and a two-gene modal. From 

their frequency distribution the recessive condition resulted in a mode 

extending from 0 to 12 percent and the dominant mode extending from 12 to 90 

percent. I have not yet found a mode of this magnitude, 12 to 90 percent, in any 

pine. The data by Bannister and others (1962), as noted earlier, showed a 

different pattern from which one might conclude a trimodal distribution. The 

current assessment of the genetic structure of α-pinene and ß-pinene in P. 

radiata is still not clear. However, one might speculate on a (0-1) pair of alleles 

for α-pinene and a (1-1) pair for ß-pinene. This would explain the trimodal 

distribution given by Bannister and others (1962). The mode proportions of 

30:46:24 were close to the theoretical one of 25:50:25 for the low, middle, and 

high modes. The fact that the low mode was about 25 percent rather than near 

zero could be explained by isomerization and by some activity by the (0-0) set 

of alleles. The modes for ß-pinene were always greater than those for α-pinene 

but still trimodal depending on the set of alleles for α-pinene, (0-0), (0-1), or (1-

1). Some of the reported studies used young and old trees. Thus some of the 

inconsistencies could be caused by the presence of a juvenile factor as was 

discussed earlier in this Chapter for P. ponderosa and for P. coulteri. 

In summary, the xylem monoterpene composition of P. radiata was 

generally reported as 20-45 percent α-pinene and complementary amounts of 

ß-pinene, i.e., 55-80 percent. The frequency distribution of the two components 

in one report tended to be trimodal, suggesting two additive alleles; in another 

report the distribution looked monomodal. Both reports were based on 35 to 40 

trees, which may not be enough. An examination of planted trees in Chile 

showed as much as 5.5 percent limonene, 13.5 percent sabinene, and 2 percent 

128 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smi

th 19 Pine Species of California Chapter 3 

myrcene in some trees. The presence of these unusual amounts of these latter 

three components is puzzling. It might be that some of the seed was P. muricata 

or a natural hybrid of P. radiata and P. muricata, because the southern variety of P. muricata can have a large amount of sabinene. 

#17. Pinus sabiniana Dougl. (Digger pine)

Pinus sabiniana is limited to California (fig. 3-38). The greater part of its 

distribution is the lower elevation of foothills surrounding the Central Valley. 

But there also are stands in certain portions of the Coast Ranges, the Siskiyou 

Mountains, and an outlying stand on the Hat Creek Rim in eastern Shasta 

County. P. sabiniana along with P. coulteri and P. torreyana comprise the big 

cone pines. Mirov (1961) reported that all early analyses found greater than 95 

percent heptane in the xylem resin volatiles of P. sabiniana. 

I analyzed trees in two stands in the counties of Sacramento and Shasta for 

a total of 99 trees (fig. 3-38); both stands were a mixture of young and old trees 

but all were greater than 40 years old. Nearly all trees in both stands had more 

than 96 percent heptane ranging from 93.6 percent to 99.8 percent (table 3-51). 

The only monoterpene in any amount was camphene, with an average of about 

0.5 percent in the Shasta stand. Nonane averaged about one percent, with a 

high of more than five percent. Nonane, like heptane, is a hydrocarbon that is 

sometimes associated with monoterpenes. The two stands differed only in the 

average amount of heptane, with about 99 percent in the southern source and 

about 98 percent in the northern source (table 3-51). The most notable difference 

between the two stands was the frequency distribution of nonane (fig. 3-39). 

The northern stand seemed to have a bimodal distribution tightly clustered 

between 0.5 and 2.5 percent with a few values at 0 percent; the southern stand 

had a large cluster at 0 percent nonane with a few values scattered all the way 

to about 6 percent. The data were insufficient for determining whether the 

difference in nonane was environmental or genetic. 

P. sabiniana and P. jeffreyi are very similar in having about 95 percent 

heptane plus small to trace amounts of several monoterpenes. However, they 

differ in that P. sabiniana does not have myrcene or ß-phellandrene, which are 

two of the more common trace components in P. jeffreyi. 

#18. Pinus torreyana Parry (Torrey pine)

P. torreyana is a rare pine found at only two locations in southern California. 

One stand of less than 6000 trees occupies a small strip of coastal land north of

San Diego (fig. 3-40). A second stand is found on the Channel Island of Santa 

Rosa, 175 miles to the northwest; this population is confined to an area of about 

800 acres and probably has fewer trees than the mainland stand. Zavarin and 

others (1967) analyzed both stands—13 mainland trees and five island trees—

for xylem monoterpenes (table 3-52).

No data on individual trees were given by Zavarin and others (1967) but it 

is apparent that the two stands differ in the amount of ß-phellandrene and 

limonene. Four other sets of trees growing at the Institute of Forest Genetics 

(IFG) from seed collected from the San Diego source showed nearly the same 

composition as Zavarin's San Diego trees (table 3-52). There was less heptane in 

the IFG-grown trees; the remaining components were nearly the same in the 

natural trees or the trees planted at the IFG, despite a large age difference. 

P. torreyana is not only rare in numbers and distribution, but is also unusual 

in apparently having a (1-1) set of alleles for limonene. It would be helpful to 

have a larger sample from both localities and to have the frequency distribution 

of the individual components for evaluating ß-phellandrene as a characteristic 

separating the two populations. If the average ß-phellandrene (8 percent) in the 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 129 
Chapter 3 19 Pine Species of California Smith 

Figure 3-38—Distribution of Pinus 

sabiniana, taken from Griffin and 

Critchfield (1972), and the location of 

the two stands that were sampled 

130 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-39—Frequency distribution 

of the amount of the noted monoterpenes and volatile components of the 

xylem resin in two stands of P. sabiniana: 

Shasta County and Sacramento County, 

men

listed on the right each dot is measuret of one tree except where indicates each represents n trees; ▲ is average of stand. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 131 
Chapter 3 19 Pine Species of California Smith 

Figure 3-40—Distribution of P. torreyana in California, taken from 

Critchfield and Little (1966). 

Table 3-51—Average , standard deviation (S.D.) and range for the xylem monoterpenes in two stands of P. 

sabiniana in California: Sacramento and Shasta County; n = number of trees in stand 

Monoterpene Sacramento (n=54) Shasta (n=44) 

S.D. min max S.D. min max 

---- percent ---- ----percent1

---- ----- percent ----- ---- percent

1

 ----

Heptane 98.6 1.4 93.6 99.8 97.7 0.9 95.3 99.4 

Nonane 0.6 1.3 0 5.7 1.3 0.6 0 2.8 

α-Pinene 0.2 0.2 0 0.7 0.2 0.1 0 0.5 

Camphene 0 0 0 0 0.5 0.4 0 1.8 

ß-Pinene 0.5 0.3 0.2 1.2 0.1 0.2 0 1.3 

Limonene 0.1 0.2 0 1.3 0.2 0.2 0 0.8 

1

 Normalized. 

Table 3-52—Average monoterpene composition of six sets of P. torreyana 

Component Set 

I II III IV V VI 

--------------------- ------------- percent 1 -------------------------------------------

Heptane 3.6 2.2 * * * * 

Nonane 2.4 1.7 2.4 1.7 0.3 1.6 

α-Pinene 2.8 2.7 2.5 2.2 2.2 2.4 

Camphene - - * * 0.4 0.2 

Undecane 7.4 6.1 7.5 8.1 8.3 8.2 

ß-Pinene * 0.2 * * * * 

Myrcene 1.7 2.9 2.9 2.9 2.8 2.6 

Limonene 73.4 84.2 84.7 85.2 84.8 84.8 

ß-Phellandrene 8.7 * - - - -

Terpinolene 0.1 0.5 * 0.3 0.7 0.4 

Set N Source of tree 1 A Source of Data 

I 7 Natural stand; Santa Rosa Island ? Zavarin and others (1967) 

II 13 Natural stand; San Diego ? Zavarin and others (1967) 

III 6 IFG arboretum; San Diego, seed 40 This report 

IV 6 IFG arboretum; San Diego, seed 45 Same trees as III 

V 8 IFG nursery; San Diego, seed 10 This report 

VI 10 IFG nursery; San Diego, seed 13 This report 

1

 Normalized; * = trace, - = zero. 

132 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smi

th 19 Pine Species of California Chapter 3 

Santa Rosa Island population was caused by some trees with moderate amounts 

and some trees with none, then one might suspect that there was an allele for ß-

phellandrene making the island population genetically different from the 

mainland population where ß-phellandrene was absent. If, however, the ßphellandrene in the Santa Rosa Island population was caused by a small 

amount in nearly all trees, then one would suspect an environmental difference. 

This situation is very similar to the two populations of P. balfouriana where 

limonene was the component in question. These differences could also be 

caused by a minor genetic effect which has not yet been explained. However, 

this uncertainty points out the great advantage of frequency distribution 

analysis over the use of x, S.D., S.E., etc. 

The composition of the trees growing at IFG, from seed collected from the 

San Diego stand, was almost identical to that of the natural population near San 

Diego; this was not the case for P. quadrifolia whose population at IFG from seed 

from San Diego differed somewhat from the natural population near San 

Diego. Also, the composition of 6- to 10-year-old seedlings from San Diego was 

essentially the same as that of mature trees. 

P. torreyana is grouped with P. sabiniana and P. coulteri as the big cone 

pines. The monoterpenes of this group of pines show little or no relationship. P. 

sabiniana is near-pure heptane; P. torreyana is near-pure limonene; and P. coulteri 

is quite variable in three monoterpenes, α-pinene, myrcene, and ßphellandrene. 

#19. Pinus washoensis Mason and Stockwell (Washoe pine) 

P. washoensis is another rare pine, though it may not be as rare as was once 

thought. It was found and described in 1938 as a small isolated stand on the 

southern slope of Mt. Rose, Nevada, which is in the central Sierra Nevada 

northeast of Lake Tahoe (Mason and Stockwell (1945) (fig.3-41). Two other 

stands have been described, one on Bald Mountain about 20 miles northwest of 

Mount Rose, the other near Patterson Meadow in the South Warner Mountains 

about 150 miles north of Mount Rose (fig. 3-41). However, quite recently several 

other stands have been located in Oregon and as far north as British Columbia 

that appear to be P. washoensis (Haller 1961). Currently, there is much 

uncertainty about the identity and distribution of P. washoensis. 

Mirov (1961) reported the xylem monoterpenes to be primarily varying 

mixtures of 3-carene and ß-pinene, plus small to trace amounts of α-pinene. 

In 1963, I sampled 28 trees of the Mount Rose population at the location of 

the type tree of Mason and Stockwell. The results (table 3-53) were generally 

similar to Mirov's, but there were differences as well: 3-carene was always high 

but still ranged widely from 49 to 70 percent; ß-pinene ranged from about 1 to 

33 percent; myrcene averaged 14 percent and ranged from 6 to 21 percent. 

I also reported on an investigation of trees at the Patterson Meadow 

population, as well as nearby populations which could be P. washoensis (Smith 

1971). The results strongly suggest that the population at Patterson Meadow may be much larger, extending 7 to 10 miles across the southern end of the 

South Warners, south of Eagle Peak. However, populations of pines farther 

north through Cedar Pass did not resemble P. washoensis but were probably 

part of the vast Cascade Northern monoterpene type of P. ponderosa noted 

earlier in this chapter. 

In the South Warner study a tree was found at a lower elevation whose 

monoterpene composition resembled a cross of P. jeffreyi with P. washoensis and 

P. ponderosa. The composition of the tree was 17 percent heptane, 2 percent 

nonane, 2 percent α-pinene, a trace of α-thujene, 4 percent ß-pinene, 55 percent 

3-carene, 6 percent myrcene, 11 percent limonene, and 3 percent terpinolene. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 133 
Chapter 3 19 Pine Species of California Smith 

Figure 3-41—Distribution of P. washoensis in 

northeastern California and northwestern 

Nevada indicated by x circled, as taken from 

Griffin and Critchfield (1972). 

Table 3-53—Average xylem monoterpene composition of 28 P. washoensis of the Mt. Rose population and 

composition of four trees selected to illustrate differences; taken from Smith (1967b) 

Monoterpene 1 

N α-p ß-p car myr lim ß-ph γ-ter terp 

------------------------------------------------------------------percent 2 --------------------------------------

28 5.0 9.8 65.6 13.9 1.7 1.1 0.2 2.8 

1 6.2 6.4 63.4 10.4 10.2 1.1 0 2.2 

1 4.5 22.6 59.9 8.9 0.7 1.2 * 2.3 

1 3.6 0.4 70.4 20.5 1.2 1.2 0.3 3.7 

1 7.0 33.1 49.9 6.6 0.6 0.6 0 2.1 

1 α-pinene, ß-pinene, 3-carene, myrcene, limonene, ß-phellandrene, γ-terpinene, terpinoline. 

2

 Normalized; * = trace. 

134 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

A. more recent study was also made of the Mt. Rose population of P. 

washoensis and the South Warner population. The averages of the individual 

stands in each area and for all trees in the area showed the two stands to be 

quite similar (table 3-54), yet they had some small differences. The frequency 

distribution of the individual components in each stand clearly showed the 

similarities (fig. 3-42). 

Little or no difference was found in the composition of P. washoensis 

between a basal tree sample and one at 20 feet (see table 8-1). 

The relationship of P. washoensis and P. ponderosa has been discussed by 

Critchfield (1984) using several characteristics including cone morphology, 

crossability, and xylem monoterpenes. To further the study of this relationship 

I compared P. washoensis from the South Warner stand and the Mt. Rose stand 

with nearby and distant sources of P. ponderosa (taken from #14 of this chapter). 

Eight stands were used (table 3-55); the smaller P. washoensis stands were 

aggregated in order to have about 40 to 60 trees in each stand. 

The coding criteria and procedures described for P. ponderosa (table 3-44) 

were used to code the composition of all trees (table 3-56). The frequency 

distribution of types of trees in each stand was determined (fig. 3-43). Stands 

were compared by coefficient of association (table 3-56). 

The coefficients of association (table 3-56) showed that the two sources of P. 

washoensis, Mt. Rose and South Warners, had strong coefficients with each 

other, though the Mahogany Ridge stand, farthest west from the Patterson 

Meadow stand, was the least strongly associated of the P. washoensis sources. 

The latter stands were poorly associated with P. ponderosa from three sources in 

the Sierra Pacific: Adin, Modoc National Forest; Pacific, Eldorado National 

Forest; and Blue Lake, Modoc National Forest. The Mahogany Ridge stand of P. 

washoensis had a coefficient of association of only 0.21 with the P. ponderosa 

stand at Blue Lake, only 2 to 3 airline miles away, but had a coefficient of 0.85 

with the P. ponderosa stand at Camas Creek, about 50 airline miles to the north. 

However, the Blue Lake stand of P. ponderosa was still more strongly associated 

with the Mahogany Ridge stand P. washoensis than are other P. ponderosa stands 

of the Sierra Pacific Region. Thus one might conclude that the Blue Lake stand 

was not pure P. ponderosa and was not strongly associated with stands in either 

the Sierra Pacific or Cascade Regions (fig. 3-43, table 3-56). It was possible that 

the P. washoensis stand at Mahogany Ridge and the P. ponderosa stand at Blue 

Lake were affecting each other through either or both cross breeding and seed 

dispersal. The Blue Lake stand of P. ponderosa may be a transitional type of P. 

ponderosa. There was speculation that such a transition zone, between Sierra 

Pacific and Cascade Regions, might be found in northeastern California and 

southern Oregon. The P. ponderosa stand at Camas Creek in the North Warner, 

which was classified as a Cascade Northern stand of P. ponderosa, had strong 

associations with all sources of P. washoensis. As Critchfield noted, it appeared 

that P. washoensis is closely related to the Cascade Northern race (resin) of P. 

ponderosa as defined earlier in this chapter. 

The Blue Lake stand contains P. ponderosa BL-6047, which was a highlimonene tree used in the latter stages of the breeding studies (see Chapter 6). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 135 
Chapter 3 19 Pine Species of California Smith 

Table 3-54—Average monoterpene composition of 11 plots of P washoensis in two stands (Mt. Rose and South Warners) and the average of each stand 

Stand Plot N Monoterpene 1 

α-p ß-p car my lim ß-ph γ-ter terp 

------------------------------------------------------ percent2

 ----------------------------------------------------------

Mt. Rose 1 23 4.9 9.9 65.7 14.0 1.3 1.1 0.2 2.9 

2 21 4.2 8.3 67.5 12.3 1.9 0.7 0.2 4.9 

3 19 4.9 12.2 66.2 9.7 0.6 1.0 0.4 5.1 

4 10 3.9 10.5 65.8 13.1 0.5 1.0 0.4 4.9 

5 10 5.1 16.1 59.3 10.7 2.3 1.3 0.3 4.9 

6 12 5.1 15.4 60.0 12.3 2.8 * * 4.0 

Total: 953 

Average: 4.6 10.8 65.5 12.1 1.3 1.0 0.3 4.4 

-----------------------------------------------------------percent2

 -------------------------------------------------------

South 7 21 5.6 9.4 63.9 13.3 2.6 0.7 0.1 4.3 

Warners 8 39 6.9 18.6 57.5 10.1 2.7 0.7 0.1 3.2 

9 20 6.1 13.2 59.9 13.9 1.6 0.8 0.2 4.0 

10 21 6.0 12.3 64.6 11.4 0.8 0.9 0.1 3.7 

11 23 6.8 12.6 66.3 8.9 0.8 0.6 0.2 3.5 

Total: 1243 

Average: 6.4 14.0 61.8 11.3 1.8 0.8 0.1 3.7 

1 α-pinene, ß-pinene, 3-carene, myrcene, limonene, ß-phellandrene, γ-terpinene, terpinolene. 2

 Normalized; * = trace. 3

 Total number of trees. 

136 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith 19 Pine Species of California Chapter 3 

Figure 3-42—Frequency distribution of 

the amount of the noted monoterpenes in 

two stands of P. washoensis; Mt. Rose and 

S

represents n trees; ▲ is stand average. 

outh Warners; each dot is measurement of 

one tree except where indicates each 

(continued on next page) 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 137 
Chapter 3 19 Pine Species of California Smith

138 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
-----------------

Smith 19 Pine Species of California Chapter 3 

Table 3-55— Coded types and actual average composition in 2 stands of P. washoensis and in 5 stands of P. 

ponderosa; see figure 3-43 for frequency of occurrences of types in the stands 

Type Coded type 1 Actual composition 1 

# 

α ß car my li α ß car my li 

- ------------------------ number --------------------------- percent 2----------------------

1 0 0 2 1 0 5 1 78 11 1 

2 0 0 2 1 1 6 1 69 10 10 

3 0 0 2 1 2 6 1 56 9 24 

4 0 0 2 2 0 5 1 71 19 * 

5 0 0 2 2 1 5 1 61 17 11 

6 0 0 2 2 2 6 2 50 22 23 

7 0 1 1 1 1 8 32 32 12 13 

8 0 1 1 1 2 7 27 27 11 24 

9 0 1 1 2 1 7 29 28 20 14 

10 0 1 1 2 2 6 26 25 19 23 

11 0 1 0 2 2 13 29 1 21 32 

12 0 1 2 0 0 6 20 66 2 1 

13 0 1 2 1 0 6 20 59 10 1 

14 0 1 2 1 1 6 21 51 10 9 

15 0 1 2 1 2 5 17 44 10 21 

16 0 1 2 2 0 5 17 55 18 1 

17 0 1 2 2 1 5 17 46 18 11 

18 0 1 2 2 2 4 13 43 21 22 

19 0 2 0 1 2 10 49 1 12 27 

20 0 2 0 2 2 9 45 * 19 25 

21 0 2 1 1 1 8 41 27 11 11 

22 0 2 1 2 1 7 37 26 16 10 

23 0 2 1 2 2 4 40 20 17 19 

24 0 2 2 1 0 5 45 38 10 1 

25 0 2 2 1 1 7 38 38 8 6 

26 1 0 0 2 2 26 2 0 18 47 

27 1 0 2 1 1 36 1 49 5 6 

28 1 1 0 2 2 24 20 1 19 36 

29 1 2 1 1 0 28 40 23 5 1 

1 α-pinene, ß-pinene, 3-carene, myrcene, limonene; minor components omitted: camphene, 

ß -phellandrene, terpinolene; see table 3-53 for amounts of minor components. 

2 Normalized; *=trace. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 139 
Chapter 3 19 Pine Species of California Smith 

Table 3-56—Coefficient of association between stands of P. washoensis and P. ponderosa on the basis of the 

frequency of types of monoterpene composition 

Location 1 Species 

---------- P. washoensis --------------- ------------------- P. ponderosa ------------------

M. Rig MR-1 MR-2 Cam-41 BL Ad-40 Pac-37 

1 Pat-Hom .84 .70 .73 .85 .21 .07 .00 

2 M. Rig .69 .86 .77 .03 .00 .06 

3 MR-1 .71 .70 .04 .01 .05 

4 MR-2 .71 .07 .01 .02 

5 Cam-41 .31 .13 .01 

6 BL .80 .58 

7 Ad-40 .71 

8 Pac-37 

1

 Patterson-Homestead (1), Mahogany Ridge (2), Mt. Rose (3,4), Camas Creek-41 (5), Blue Lake (6), 

Adin-40 (7), Pacific-37 (8). 

Figure 3-43—Distribution of types 

of composition in two stands of P. 

washoensis and four stands of P. ponderosa; distribution was normalized 

for each stand. 

140 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Chapter 4 

Monoterpene Composition of 88 Hybrids 

and 24 Parent Species at the Institute of 

Forest Genetics 

Summary: This chapter catalogs the xylem monoterpene composition of 88 

intra- and interspecific pine hybrids and 24 parent species growing in the 

arboretum at the Institute of Forest Genetics, near Placerville, California. Most 

of the parent species were from North America, but a few were from Central 

America and Eurasia. Much of the information is about P. ponderosa, P. jeffreyi, 

P. coulteri, and P. taeda. The number of trees sampled for a given parent or 

hybrid was usually small, and only generalized statements can be made about 

monoterpenes; likewise, the actual parents of most hybrids were almost always 

unavailable for terpene analysis. In many cases the pollen was a mixture of 

trees; therefore, conclusions were almost always based on the composition of 

the parent as a species. The composition of hybrids was usually intermediate, 

in a general sense, between the two parent species; the lack of close 

intermediacy would appear to be attributed to an unequal contribution of 

alleles by the two parent trees in an additive allele system. A given monoterpene 

can be lost in the first backcross. Some hybrids had monoterpenes that had not 

been reported in the parents, suggesting that the parent species had not been 

adequately sampled. 

The xylem moneterpene composition was determined for many of the intraand interspecific pine hybrids that were developed at the East Arboretum of 

the USDA Forest Service's Institute of Forest Genetics (IFG), near Placerville, 

California, from about 1935 to about 1965. Therefore, all trees were older than 

20 years at the time of this report, and many were older than 40 years. In all but 

a few cases, the number of trees available was not sufficient to determine the 

extent of variation in the composition of an individual cross. This report is 

fairly extensive and representative of the trees available in the East Arboretum 

at IFG, but it is not at all complete. The breeding procedures used to develop 

the hybrids were described by Cumming and Righter (1948). Included in the 

sampling was the composition of some of the parent tree species growing in the 

same arboretum. Much of the pollen used in the breeding was a mix of a 

number of trees of that species or hybrid. The basic objective of much of the 

early breeding was to determine crossability of species and hybrids as well as 

the appearance and characteristics of the progeny in general. It was thought 

that the use of a pollen mix would lower the likelihood of failure because of 

individual tree incompatibility. However, the use of pollen mix did reduce the 

inference that can be made about the progeny. The report in this volume 

touches upon one of the objectives of the breeding program: the characteristics 

of the progeny. All the trees reported were still growing at IFG, nearly all in the 

East Arboretum. Included in this report were some of the data of an earlier 

report from the same arboretum (Smith 1967a); however, these trees were 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 141 
Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

removed in a 1966 thinning of the arboretum. Where appropriate, reference 

will be to Mirov's (1961) report, and to other reports in order to provide 

information about parent species. I found Mirov's report to be correct in 

identifying components that were present. However, in some instances he 

failed to report the presence of components—often occurring in small to 

moderate amounts—which have been found since his work. This could be 

attributed to lack of extensive sampling or to the lack of more sensitive 

analytical procedures. Nevertheless, there was general agreement in the 

qualitative composition of this report and that of other reports. There were 

instances of quantitative differences, but that was to be expected considering 

the general variation found in the monoterpene composition of many pines and 

the action of modifying factors. 

The presence of small to trace amounts of several terpenes, usually called 

minor components, in many species and hybrids requires some comment. One 

might speculate that these were by-products of the synthesis of the major 

monoterpenes in a given species or hybrid, or that they were products of 

isomerization of the major monoterpenes, or that there was a secondary genetic 

mechanism. Likewise, the major components were found in small amounts in 

many trees, even in species in which they were major components. And thus 

there was the possibility that the amount of a given component could be 

produced by both a major and minor mechanism. Only two clear linkages of 

major with minor components was found: the relationship of terpinolene to 3-

carene with a ratio varying from 1 to 20 to about 1 to 10 depending on the 

species, and the relationship of terpinolene to sabinene with a ratio varying 

from 1:1 to 1:2, depending on the species. 

The classification and nomenclature of pines used in this section will be 

that given by Critchfield and Little (1966). Changes made since the time the 

breeding was done will be noted in the sections dealing with the particular 

species. However, there still was uncertainty about the varietal status of some 

pines, notably P. ponderosa, P. contorta, P. halepensis, P. pinaster, P. montezumae. 

The taxonomic discussions will be few and brief since the report's objective was 

to present the xylem monoterpene characteristics of the species and hybrids. A 

botanical description of many of the hybrids was given by Little and Righter 

(1965); these will be noted within the text where appropriate without comment. 

Trees were sampled by the 9/16-inch macro-tap and 5-cc vial or by minitap with the tap hole acting as the resin collector, between 1981 and 1988. 

Sampling and analysis were described under "Procedures" in Chapter 2. Both 

pentane and acetone preparations were made for trees where the presence of 

heptane was suspected. 

The monoterpene compositions of the individual parent species or hybrid 

used in a cross were not available; therefore, in all cases the report was based on 

generalized composition of the parent trees used in the crosses. 

Some General Statements About Monoterpenes 

The following generalized statements can be made from an examination of all 

the listings. 

• The gene structure for xylem monoterpenes might be either two 

additive alleles at a single locus, polygenic, or a dominant/recessive 

pair of alleles. The evidence seemed strongest for additive alleles. 

There was some evidence that under certain circumstances, not yet 

understood, the (0-0) pair of alleles might have a small degree of 

activity rather than zero activity. 

142 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

• Trace or small amounts of monoterpenes can be present although the 

gene for that monoterpene may be absent; this may be caused by 

isomerization from other monoterpenes or by-products of 

biosynthesis. 

• The evidence suggested that the following monoterpenes or 

associated hydrocarbons were directly controlled in xylem resin of 

pines by genes: heptane, nonane, α–pinene, ß–pinene, 3-carene, 

sabinene, myrcene, limonene, and ß–phellandrene, whereas the 

following appeared to be produced by isomerization, or by some 

other mechanism as yet not understood, or by direct association with 

a gene-controlled monoterpene: nonane, undecane, camphene, α– 

phellandrene, γ–terpinene, ocimene, terpinolene, α–thujene. 

• Because there appeared to be a fixed amount of a five-carbon 

precursor for the biosynthesis of monoterpenes, there was, in effect, 

"competition" among the monoterpene genes for this fixed amount. 

And there may be unequal competition for the precursor. 

• The expression of one gene was dependent on both its allelic structure 

as well as that of the competing genes. For example, a (1-1) pair of 

alleles for α–pinene will produce a monoterpene composition of 

nearly all α–pinene if all other pairs of alleles for other monoterpenes 

were (0-0). But, if there was a (1-1) or (0-1) pair of alleles for one or 

more of the other monoterpenes, the composition will not be nearly 

all α-pinene. Instead, it will be divided up among the components 

that have (1-1) or (0-1) alleles or possibly even (0-0) in some instances. 

If additive alleles were the mechanism, then interspecific progeny 

might not be intermediate in composition because one parent could 

have more alleles than the other. Thus, with competition for a fixed 

amount of precursor, the monoterpene composition of the progeny 

would be more like one parent than the other. 

Eighty-eight intra- and interspecific crosses and 24 parent species were 

listed in this chapter. The most common hybrids were those of P. ponderosa and 

P. jeffreyi, and this reflected the emphasis of the breeding programs at IFG from 

about 1935 to 1965. The listing was alphabetical by the female parent or the 

female parent of the hybrid when used as a female. There have been a few 

taxonomic changes since the breeding was done; these will be noted in the text. 

Explanation of Format 

For each species or cross, the number of progeny analyzed and their average 

normalized percent composition will be listed first below the lined heading. 

This will be followed by individual listing of the composition of one or more of 

the trees that were selected from the total number to show the variation in 

composition of individual trees. Below these individually listed trees may be 

given the composition listed by Smith (1967a) of the same species or hybrid, or 

by Mirov (1961) of one or more of the parent species involved in the cross. 

Mirov's sample was usually obtained by aggregating the resin from several 

trees; therefore, no number of trees was given when citing his report. Where 

appropriate, the data of Chapter 3 will be referenced. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 143 
Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

The "Source" column designates the origin of the data for each row 

as follows: 

TR = This Report 

M =Mirov (1961) 

S = Smith (1967a) 

All other references will be footnoted in the customary way. 

The number of trees, "n," follows "Source." 

All trees are listed in the conventional way with the female parent preceding 

the "X" and male parent following it. Hybrids are designated by a period 

between two species names and with an underline covering both trees. 

Asterisks (**) indicate hybrids that were described by Little and 

Righter (1965). 

Abbreviations of monoterpenes are as follows: 

hep = heptane ß–p = ß–pinene lim = limonene 

non = nonane car = 3-carene ß–ph = ß–phellandrene 

and = undecane sab = sabinene γ–ter = gamma-terpinene 

α–p = α–pinene myr = myrcene oci = ocimene 

cam = camphene α–ph = α–phellandrene ter = terpinolene 

α–th = α–thujene * = trace amount - = zero amount 

Percentages are given in digits, * indicates trace, - indicates zero. Where the 

value space is blank, no value was available from the source. 

Most cited reports gave the number of trees sampled and normalized 

composition, but there were a few cases where this was not done. 

#1. Pinus attenuata 

Source n α–p cam ß–p car myr lim ß–-ph 

---------------------------percent: normalized ------------------------

TR 5 96.4 0.4 1.0 0.6 1.3 0.2 0.2 

TR 1 97.2 - 1.9 - 0.5 0.2 0.1 

TR 1 92.2 0.2 1.1 2.6 3.5 0.1 0.2 

M 98.0 - - - - - -

The above format is explained in the introduction to this chapter. 

This species is largely limited to California, though its distribution does 

extend northward into southern Oregon. Five trees were sampled, and all had 

the same composition, nearly pure α–pinene, with small amounts of camphene, 

ß–pinene, 3-carene, myrcene, limonene, and ß–phellandrene. Only α–pinene 

and myrcene had amounts greater than 1 percent. This composition agreed 

with all previous work (Mirov 1961, Williams and Bannister 1962) and with a 

large sample study in this report (see Chapter 3, #3). It can easily be concluded that 

P. attenuata has a (1-1) set of additive alleles for α–pinene. It might also be concluded 

that the small amounts of the other terpenes were products of isomerization or 

biosynthetic by products and reflect the natural variation in this property. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#2. P. attenuata x P. radiata** 

Source n α–p cam ß–p car myr lim ß–-ph 

-------------------------- percent: normalized 

TR 7 63.9 - 35.2 0.1 0.5 0.2 0.4 

TR 1 68.8 - 30.7 - 0.4 0.1 0.1 

TR 1 56.9 - 42.4 - 0.3 0.2 0.3 

S 1 59.0 2.0 38.0 - 1.0 1.0 1.0 

The above format is explained in the introduction to this chapter. 

This hybrid was considered one of the early successes of pine hybridization 

at IFG. It presumably combined the growth properties of P. radiata with the 

cold and drought tolerance of P. attenuata. The hybrid was expected to be suited 

for the lower elevations of the Sierra Nevada. 

Seven trees were sampled, and the average was 64 percent α–pinene and 35 

percent ß–pinene with small amounts of camphene, 3-carene, myrcene, 

limonene, ß–phellandrene. The variation among the seven trees was not great, 

with α–pinene ranging from 69 to 57 percent, and ß–pinene from 42 to 31 

percent. The range of these two components was much greater in a sample of 

300 4-year-old trees (Strauss and Critchfield 1982). However, they were using 

the composition of very young trees, and the age of xylem sampled was, 

apparently, 3 to 4 years. In that study (Strauss and Critchfield 1982), it was 

concluded that ß–pinene was controlled by a dominant/recessive mechanism, 

as was also concluded earlier (Forde 1964). Neither report gave the range in 

composition of individual trees which would be helpful in assessing the 

relationship of α–pinene to ß–pinene and in determining the modal 

characteristics of the frequency distribution. 

#3. P. attenuata x P. muricata** 

Source n α–p cam ß–p car sab myr lim ß–ph ter 

------------------------------- percent: normal 

TR 3 63.9 0.3 3.2 - 21.5 1.0 0.3 * 9.8 

TR 1 40.6 0.1 5.7 - 35.3 1.9 0.4 * 16.0 

TR 1 83.7 0.6 2.1 - 7.9 0.1 0.6 0.1 5.1 

TR 1 67.3 0.3 1.8 - 21.2 1.0 * * 8.4 

S 1 44.0 1.0 3.0 * 34.0 1.0 1.0 1.0 16.0 

1

Listed as P. remorata when breeding was done. 

The above format is explained in the introduction to this chapter. 

The male parent was designated as P. remorata at the time the breeding was 

done. However, that species is now considered part of P. muricata. The three 

trees sampled had a wide range in composition, reflecting the great variation in 

the male parent (Forde and Blight 1964, Mirov and others 1966, Chapter 3 of 

this volume, #13). With a wider source of male parents, one would expect even 

a greater variety in composition. The composition of two of the trees suggests 

that the male parent was high in sabinene, which is characteristic of the sources 

of P. murcata in Southern California. Three of the trees also showed the general 

2:1 relationship of sabinene to terpinolene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#4. Pinus brutia 

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter 

--------------------------------------percent: normalized 

TR 3 55.1 0.3 20.1 19.8 1.7 0.2 0.9 * 1.8 

TR 1 72.1 0.4 17.5 7.1 1.4 * 1.1 - 0.2 

TR 1 40.5 0.2 28.5 25.9 1.6 - 0.8 - 2.4 

M 62.0 17.0 13.0 2.0 

The above format is explained in the introduction to this chapter. 

This was designated as P. halepensis var. brutia when breeding was done, 

but recent isozyme research established P. brutia as a separate species (Conkle 

and others 1988). The composition of these three trees somewhat resembled 

those reported under item #5 below, P. brutia x P. halepensis, although they 

tended to more closely resemble P. halepensis x wind. They did not resemble the 

P. halepensis reported by Mirov and others (1966) who reported P. halepensis 

with about 95 percent α–pinene, P. brutia with about 62 percent α–pinene, and 

the remaining 30 percent about equally divided between ß–pinene and 3-

carene. (Also see P. halepensis, #32 below.) 

#5. P. brutia x P. halepensis 

Source n α–p cam ß–p car myr lim ß–ph ter 

----------------------------percent: normalized 

TR 5 79.8 0.3 5.1 8.1 0.7 4.3 0.6 0.9 

TR 1 78.7 0.6 11.6 - 1.5 6.0 1.6 -

TR 1 95.8 0.2 0.8 - * 3.0 - 0.1 

TR 1 47.6 * 0.5 40. 1.0 5.9 * 4.3 

The above format is explained in the introduction to this chapter. 

These progeny were reciprocals of item #33 below, and the results were 

quite similar both in average amounts and in the variable kinds of composition. 

Both P. brutia (#4) and P. halepensis (#32) were generally low or lacking 

limonene, although one of the P. halepensis listed for #32 had 7 percent limonene. 

From the above data, one might speculate that limonene was higher than 

reported for some P. halepensis. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#6. Pinus contorta var contorta x wind 

Source n α–p cam ß–p car sab α–ph lim ß–ph ter 

----------------------------------percent: normalized 

S 1 9.0 1.0 4.0 5.0 2.0 1.0 2.2 2.0 73.0 1.0 

M - 5.0 - - - - - - - 95.0 -

The above format is explained in the introduction to this chapter. 

Only one tree was reported and that was from a previous publication (Smith 

1967a). Mirov (1961) reported this variety as about 5 percent α–pinene and 95 

percent ß–phellandrene. The composition for the one tree listed above was well 

within the range of that reported in a range-wide study of P. contorta (Smith 

1985). For more information on this species, see Chapter 3. 

#7. P. contorta var. murrayana x P. contorta var. contorta 

Source n hep α–p cam ß–p car sab α–ph myr lim ß–ph ter 

------------------------------------------ percent: normalized 

S 1 * 6.0 1.0 8.0 2.0 2.0 1.0 3.0 2.0 76.0 * 

S 1 * 8.0 1.0 4.0 18. 2.0 1.0 3.0 2.0 59.0 1.0 

The above format is explained in the introduction to this chapter. 

These two trees, half-siblings and reported earlier (Smith 1967a), fell well 

within the expected range of compositions. There was a noticeable difference 

between the two half-siblings in both 3-carene and ß–phellandrene. 

#8. P. contorta x P. contorta var. murrayana 

Source n α–p cam ß–p car sab α–ph myr lim ß–-ph ter 

------------------------------------ percent: normalized 

TR 1 7.7 0.5 15.4 37.5 0.5 - 1.5 2.3 34.6 * 

The above format is explained in the introduction to this chapter. 

The composition of the one tree was well within the expected: high in ß– 

phellandrene and 3-carene, moderate amounts of ß–pinene and α–pinene, and 

small to trace amounts of camphene, sabinene, myrcene, limonene, and 

terpinolene. The absence of terpinoline in this one tree was puzzling because 

one would expect it to be between 1.5 and 2.0 percent since it was almost 

always at a ratio of 1:15 to 1:20 with 3-carene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#9. P. contorta var. murrayana x P. contorta var. bolanderi 

Source n α–p cam ß–p car sab α–ph myr lim ß–ph ter 

-------------------------------- percent: normalized 

TR 10 5.8 0.6 5.4 9.3 1.2 0.3 2.6 0.8 74.0 0.2 

TR 1 7.1 2.8 13.4 2.5 * - * * 74.2 -

TR 1 5.0 0.1 1.7 - 1.3 0.5 2.8 1.3 87.3 * 

TR 1 3.5 - 0.4 30.9 5.2 - 1.1 - 57.6 57.6 1.4 

TR 1 6.6 0.5 6.2 3.9 * * 3.7 78.6 78.6 0.4 

The above format is explained in the introduction to this chapter. 

The intraspecific hybrids of these two varieties of P. contorta showed 

considerable variation in ß–pinene, 3-carene, sabinene, and ß–phellandrene. 

However, the range in composition suggested that the var. murrayana and var. 

bolanderi cannot be separated on the basis of monoterpene composition. 

#10. P. contorta var. murrayana x P. banksiana** 

Source n α–p cam ß–p car sab α–ph myr lim ß–ph ter 

-------------------------------------percent: normalized-----------------------

TR 9 58.0 0.1 20.2 1.6 0.2 * 0.9 18.1 * 

TR 1 91.3 - 7.8 - - - 1.0 - - -

TR 1 49.6 0.2 25.1 2.9 * * 1.2 0.4 20.6 * 

TR 1 65.8 0.4 13.5 - - - 1.0 - 19.3 -

S 1 55.0 1.0 23.0 2.0 * * 2.0 1.0 18.0 -

The above format is explained in the introduction to this chapter. 

The nine trees reported here showed a general intermediacy between the 

two parents. Mirov (1956), reporting an examination of trees in Alberta, Canada, 

where the two species P. contorta and P. banksiana were sympatric, showed that 

many trees had resin properties intermediate between the two parent species. 

Intermediate composition was reported for hybrids of controlled pollination 

(Zavarin and others 1969). This latter study also gave some evidence that the 

genes for the two species acted independently of each other. The one tree 

without ß–phellandrene and with 91 percent α–pinene was completely off 

scale for any progeny of the two species and might be considered a rogue. A 

more comprehensive treatment of hybridization of P. contorta and P. banksiana 

was given by Zavarin and others (1969). In that report Zavarin and others were 

puzzled by the lack of ß–phellandrene in some of the hybrids. They may have 

been working with young hybrids, and it will be shown in other parts of this 

volume (see P. coulteri, Chapter 3) that the production of ß–phellandrene may 

be greatly suppressed in young trees and that the amount of ß–phellandrene 

increased with age of the tree. Mirov (1961) listed P. banksiana with 85 percent 

α–pinene and 10 percent ß–pinene. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#11. P. contorta var. murrayana. banksiana x P. banksiana 

Source n α–p cam ß–p car sab α–ph myr lim ß–ph 

--------------------------percent: normalized 

TR 1 81.9 3.0 15.0 - - - - - -

The above format is explained in the introduction to this chapter. 

This backcross was nearly all α–pinene and ß–pinene. The lack of ß– 

phellandrene can be explained by starting with a (1-1) set of alleles for 

ß–phellandrene in the P. contorta parent, a reduction to a (0-1) set in the F-1 

generation, and a further reduction to a (0-0) set in this listed tree. These results 

supported either the dominant/recessive alleles or an additive set of alleles for 

ß–phellandrene. However, Smith (1983) found strong evidence for additive 

alleles for ß–phellandrene in a range-wide study of P. contorta. 

#12. P. contorta var. murrayana.banksiana x P. contorta var. 

murrayana.banksiana 

Source n α–p cam ß–p car sab α–ph myr lim ß–ph ter 

------------------------------------- percent: normalized 

TR 9 56.4 0.3 20.6 1.4 0.1 0.1 1.5 0.6 19.0 0.2 

TR 1 34.1 0.1 14.1 4.1 - - 2.4 0.4 44.9 0.1 

TR 1 11.9 0.2 54.9 * - - 1.6 0.6 30.3 0.3 

TR 1 85.4 * 10.5 1.7 - - 1.1 0.4 0.7 0.2 

TR 1 57.8 1.0 19.8 0.2 0.2 0.3 1.4 * 19.0 * 

The above format is explained in the introduction to this chapter. 

These backcrosses had a wide range of compositions as illustrated by the 

individually listed trees. Though Mirov (1961) reports only 10 percent α– 

pinene in P. banksiana, Zavarin and others (1969) reported a considerable range 

from about 40 percent to 90 percent and reported ß–pinene ranging from about 

20 percent to about 50 percent. These values were derived from data given as 

normalized composition of total resin. Therefore, the variation and range in 

these nine trees were expected when the variation of the two parent species was 

considered. Among these F2 generation progeny one can see P. banksiana-like 

progeny with high α–pinene and moderate ß–pinene and P. contorta-like 

progeny with high ß–phellandrene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#13. Pinus coulteri x wind 

Source n hep non α–p und cam ß–p car sab myr lim ß–ph ter 

percent: normalized 

S 1 * * 53.0 2.0 2.0 2.0 * 2.0 2.0 1.0 36.0 1.0 

S 1 1.0 1.0 43.0 4.0 * 3.0 * * 15.0 5.0 28.0 * 

M - 5.0 - 33.0 10.0 - - - - - - 33.0 * 

The above format is explained in the introduction to this chapter. 

The first two trees listed were reported earlier (Smith 1967a), and their 

composition was well within that expected. This species was reported here 

because it was used in a number of crosses involving P. ponderosa and P. jeffreyi. 

(See Chapter 3, #6 of this volume for additional data on P. coulteri.) Nearly all of 

the hybridization work done with P. coulteri was with the male tree. When 

mature, the very large, heavy, and heavily armed cone of P. coulteri would be 

difficult to handle, although this should be no problem with very young 

conelets at the time of pollination. 

#14. Pinus echinata 

Source n α–p cam ß–p myr lim ß–ph 

-------------------- percent: normalized 

TR 11 65.1 0.1 31.8 1.5 1.1 0.6 

TR 1 75.5 - 23.5 0.5 0.2 2.0 

TR 1 38.2 * 59.6 0.9 0.5 0.9 

TR 1 60.0 0.3 37.6 1.1 * 1.1 

TR 1 89.3 0.5 8.5 1.2 0.4 0.1 

M 1 85.0 - 11.0 - - -

The above format is explained in the introduction to this chapter. 

The composition of this species was essentially varying percentages of α– 

pinene and ß–pinene, and Mirov (1961) reported the same. The wide range in 

both components suggested that there can be (0-0), (0-1), or (1-1) sets of additive 

alleles. Coyne and Keith (1972) report a wide range in both α–pinene, 20 to 90 

percent, and ß–pinene, 10 to 70 percent. Their average composition was 48 

percent α–pinene, 48 percent ß–pinene and 1 percent camphene, myrcene, 

limonene, and ß–phellandrene. Neither the α–pinene nor ß–pinene was absent 

from any trees; this suggested the isomerization of one from the other when the 

first had a (0-0) set of alleles. It could also suggest that the (0-0) additive set or 

the (r-r) set, if one considered the dominant/recessive structure, had some 

degree of activity. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#15. P. echinata x P. taeda** 

Source n α–p cam ß–p myr lim ß–ph 

--------------------------- percent: normalized 

TR 38 64.5 0.2 30.9 2.2 1.4 0.6 

TR 1 62.5 0.1 30.7 0.9 4.9 0.9 

TR 1 76.9 - 16.4 5.7 0.9 0.1 

TR 1 45.0 0.4 51.3 0.8 1.8 0.8 

TR 1 89.3 0.5 8.5 1.2 0.4 0.1 

TR 1 96.8 - 2.9 0.1 0.2 * 

S 1 65.2 1.1 30.1 0.7 2.5 0.4 

The above format is explained in the introduction to this chapter. 

This was one of the more common hybrids in the arboretum. Both α– 

pinene and ß–pinene tend to have a trimodal distribution, although the percent 

of α–pinene was about twice that of ß–pinene. The one tree reported earlier 

(Smith 1967a) had just about the same composition as the 38 trees reported 

here. Although each species had less than 20 percent ß–pinene, some of the 

progeny were greater than 20 percent. This suggested that both species had a 

(0-1) set of additive alleles for ß–pinene. But if this were so, some trees with 

high ß–pinene, i.e, (1-1) set, would be expected. Coyne and Keith (1972) showed 

enough limonene to suggest control of gene level—more than 25 percent in both 

parents—that one would expect a few progeny with fair amounts of limonene, 

but this did not occur. The range in the composition of parent trees used may 

have been too small for a confident statement of monoterpenes in this report. 

#16. P. echinata.taeda x P. taeda 

Source n α–p cam ß–p myr lim ß–ph 

TR 2 

percent: normalized 

65.0 0.4 29.8 4.3 - 0.5 

The above format is explained in the introduction to this chapter. 

These two backcrosses had almost the same composition as the hybrid 

parent in #15 above. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#17. P. echinata x P. echinata.elliottii 

Source n α–p cam ß–p myr lim ß–ph 

------------------------------ percent: normalized 

TR 8 56.7 0.4 32.4 0.8 2.2 7.6 

TR 1 37.7 0.3 38.2 1.1 1.1 21.5 

TR 1 56.5 0.3 39.7 0.8 1.6 1.0 

TR 1 61.0 0.4 30.3 * 4.5 3.7 

The above format is explained in the introduction to this chapter. 

These eight backcrosses showed the predominance of α–pinene and ß– 

pinene, but did not show the variation for either component that one might 

expect from the variation found in the previous listing, P. echinata. There was a 

wide range in ß–phellandrene, a component usually in moderate and variable 

amounts in P. elliottii. 

#18. P. echinata.taeda x P. echinata.elliottii 

Source n α–p cam ß–p myr lim ß–ph 

------------------percent: normalized -----------------------

TR 2 47.5 0.3 33.5 9.2 * 9.5 

TR 1 54.0 0.2 29.9 7.3 * 8.7 

The above format is explained in the introduction to this chapter. 

Although only two trees were sampled, they expressed all three parents: α– 

pinene and ß–pinene for P. taeda and P. echinata, myrcene for P. taeda and P. 

elliottii, and ß–phellandrene for P. elliottii. 

#19. P. echinata.taeda x P. rigida.taeda 

Source n α–p cam ß–p myr lim ß–ph 

percent: normalized --------------------------

TR 3 60.8 0.2 27.9 6.4 * 4.6 

TR 1 36.6 0.1 39.7 10.7 - 12.8 

TR 1 77.5 0.3 18.3 3.5 - 0.5 

The above format is explained in the introduction to this chapter. 

The three trees sampled were quite variable in four components: α–pinene, 

37 to 78 percent; ß–pinene, 18 to 40 percent; myrcene, 4 to 11 percent; and ß– 

phellandrene, from trace to 13 percent, suggesting that one or more of the three 

parents could have a (0-1) set of additive alleles for one or more of the four 

variable components. 

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#20. Pinus elliottii var. elliottii 

Source n α–p cam ß–P myr lim ß–ph 

--------------------------- percent: normalized ---------------------

TR 5 73.0 0.5 17.0 1.2 0.5 7.9 

TR 1 71.0 0.3 27.5 0.8 - 0.5 

TR 1 77.4 0.5 9.2 1.6 0.5 10.8 

TR 1 71.3 0.6 11.2 1.4 0.7 14.7 

M 75.0 - 21.0 - - -

The above format is explained in the introduction to this chapter. 

The five trees sampled showed very little variability in α–pinene but sizable 

variability in ß–pinene and ß–phellandrene, suggesting a (1-1) set of additive 

alleles for α–pinene and a (0-1) set for both ß–pinene and ß–phellandrene. The 

average of the five trees was very similar to Mirov's (1961) report. At one time 

P. caribaea was a name given to what is now P. elliottii var. elliottii. 

#21. Pinus engelmannii 

Source n α–p cam ß–p car sab myr lim ß–ph ter 

---------------------------percent: normalized --------------------------

TR 7 96.4 0.1 0.7 - - 0.9 1.5 * 0.2 

TR 1 98.3 0.2 0.7 - - 0.4 0.4 - -

TR 1 93.8 * 0.9 - - 1.0 2.2 - 1.9 

TR 1 93.6 0.2 0.1 - - 0.8 5.4 - -

M - 80.0 - 2.0 - - - 2.0 - -

S 1 95.0 2.0 2.0 - - 1.0 * * -

The above format is explained in the introduction to this chapter. 

These seven trees were nearly identical in composition. All seven were 

simply designated as P. engelmannii while item #22, which follows, was 

designated as P. engelmannii x w. There should be no difference if one assumes 

that the "wind" (w) was in a natural stand. P. engelmannii appeared to have a (1-

1) set of alleles for α-pinene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#22. P. engelmannii x wind 

Source n α–p cam ß–p car sab myr lim ß–ph ter 

percent: normalized 

TR 8 74.2 0.1 9.8 8.5 - 3.5 2.5 0.7 0.7 

TR 1 97.7 0.3 0.6 - - 0.7 0.6 0.1 -

TR 1 28.5 0.1 19.3 36.9 - 10.4 * 1.0 3.8 

TR 1 44.8 0.1 43.8 - - 9.9 * 1.3 -

The above format is explained in the introduction to this chapter. 

This set of trees and the previous set, #21, were designated differently in 

the arboretum, and the separate designations are retained here. Also, some of 

the trees were labelled P. apacheca which was a former name for P. engelmannii. 

Some botanists believe this tree is a southern form of P. ponderosa, and that it 

greatly resembles the southwestern form P. ponderosa var. arizonica in southern 

Arizona, particularly the Coronado ecotype (See Chapter 3, #14). The composition 

of the eight trees, reported as item #22 and labelled P. engelmannii x wind, 

showed large variability in α–pinene, ß–pinene, and myrcene. One might suspect 

that the "wind" parents of this set might have included P. ponderosa or P. 

ponderosa var. arizonica. Both earlier reports of P. engelmannii (Mirov 1961, Smith 

1967a) showed that the monoterpene portion was nearly all α–pinene. Therefore, 

some of the wind parents were not, more than likely, P. engelmannii. 

#23. P. engelmannii x P. ponderosa var. scopulorum** 

Source n α–p cam ß–p car myr lim ß–ph ter 

---------------------------percent: normalized 

S 1 17 * 1 73 2 1 1 4 

The above format is explained in the introduction to this chapter. 

This one tree, reported earlier (Smith 1967a), showed nearly all characteristics of 

var. scopulorum with high 3-carene and only moderate α–pinene. The ratio of 3-carene 

to terpinolene is close to the expected, between 20:1 and 15:1. 

#24. P. engelmannii x P. ponderosa var. arizonica** 

Source n α–p cam ß–p car sab myr lim ß–ph ter 

-----------------------------percent: normalized ----------------------

TR 5 87.9 0.1 9.9 - - 0.7 0.7 0.3 

TR 1 98.0 0.1 0.4 - - 0.6 0.3 0.2 -

TR 1 51.6 0.1 46.3 - - 0.5 0.1 1.1 -

The above format is explained in the introduction to this chapter. 

These hybrids closely resembled the composition of the previous listing, #22, 

of P. engelmannii x wind; the five progeny resembled either P. engelmannii with nearpure α–pinene or P. ponderosa var. arizonica with considerable amounts of ß–pinene. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#25. P. engelmanni x P. ponderosa 

Source n α–p cam ß–p car myr lim ß–-ph γ–ter ter 

-------------------------------- percent: normalized 

TR 3 30.9 0.1 12.2 34.2 6.5 12.9 0.3 * 2.7 

TR 1 31.0 * 23.3 30.2 4.2 8.3 * * 2.9 

TR 1 32.0 * 2.5 39.0 8.5 15.1 * 2.8 

The above format is explained in the introduction to this chapter. 

The three hybrids showed the effect of both parents: α–pinene of P. 

engelmannii and ß–pinene, 3-carene, and limonene of P. ponderosa. The 

composition of the three trees suggested that intermediacy of composition 

between two parents will hold only so long as two have equal numbers of 

active gene loci. Here, P. engelmannii probably had only one active gene locus, 

α-pinene; P. ponderosa had at least three: ß–pinene, 3-carene, and limonene. 

Therefore, the progeny were not intermediate for α-pinene, at about 45 percent, 

but were more characteristic of α-pinene in P. ponderosa. 

#26. P. engelmannii x P. jeffreyi.ponderosa 

Source n hep α–p cam ß–p car myr lim ß–ph ter 

------------------------------percent: normalized 

TR 6 0.5 49.8 0.1 16.0 21.5 5.8 3.7 1.2 1.4 

TR 1 1.0 39.9 * 32.4 20.0 6.0 * 0.8 0.9 

TR 1 * 82.1 * 1.1 9.4 6.6 - 0.5 * 

TR 1 * 33.5 0.1 0.6 42.5 5.6 14.4 - 3.3 

The above format is explained in the introduction to this chapter. 

All trees had only a small but measurable amount of heptane. Thus, the 

effect of P. jeffreyi had been nearly lost in only two generations; yet one might 

ask why there were still measurable amounts of heptane. That is, one would 

expect either 0 percent or 10 to 20 percent. Two of three trees, listed individually, 

essentially resembled a cross of P. engelmannii with P. ponderosa, as in item #25. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#27. Pinus flexilis 

Source n non α–p und cam ß–p car sab myr lim ß–ph ter 

------------------------- percent: normalized 

TR 2 68.8 3.3 * 19.4 4.5 1.4 0.5 0.8 1.6 

TR 1 71.7 5.3 * 11.4 7.4 1.5 0.3 0.4 2.1 

M - 80.0 - - - - - - - - -

S 1 4.0 28.0 8.0 * 5.0 35.0 13.0 2.0 1.0 1.0 6.0 

The above format is explained in the introduction to this chapter. 

This species was far more variable than P. griffithii (formerly P. excelsa) used 

as the male parent in #28, with a large amount of α–pinene and a moderate 

amount of ß–pinene, sabinene, and undecane. Smith (1967a) reported one tree 

with 28 percent α–pinene, 35 percent 3-carene and 13 percent sabinene with 6 

percent terpinolene and trace to small amounts of nonane, undecane, ß–pinene, 

limonene, and ß–phellandrene. Additional data on P. flexilis, Chapter 3, #8, 

showed a great range in its composition. 

#28. P. flexilis x P. griffithii** 

Source n α–p und cam ß–p car sab myr lim ß–ph ter 

-------------------------- percent: normalized 

TR 3 41.9 2.9 * 49.1 1.6 0.5 0.3 3.7 

S 1 85.0 8.0 * 2.0 3.0 1.0 * * 1.0 

The above format is explained in the introduction to this chapter. 

The male parent was labelled P. excelsa; it is now considered P. griffithii (see 

#30 below). The composition of the three progeny did not show the 

intermediacy of α–pinene. Both parents were high in α–pinene, but when 3-

carene was a component of the P. flexilis parent, the progeny had only moderate 

amounts of α–pinene. 

#29. Pinus greggii x wind 

Source n α–p com ß–p car a-ph myr lim ß–ph ter 

-------------------------- percent: normalized 

TR 5 6.9 0.4 0.7 7.2 0.9 1.2 13.2 69.5 0.3 

TR 1 9.4 0.6 0.8 0.5 1.0 1.6 2.6 83.4 -

TR 1 5.9 0.2 0.5 12.6 0.5 * 22.5 57.6 0.2 

TR 1 5.5 0.3 0.5 22.6 1.3 2.5 1.3 64.5 0.4 

M - large large some 

1 7.3 1.4 0.8 32.4 45.3 

M No values given, just quantitative terms. 1 Lockhart (1990a) 

The above format is explained in the introduction to this chapter. 

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The five trees examined were quite variable in 3-carene, limonene, and 

ß–phellandrene. Mirov (1961) was able to find only large amounts of α–pinene 

and ß–pinene, but was unable to resolve the remainder of his analytical sample, 

though he speculated on ß–phellandrene and limonene. As will be frequently 

noted, many of the pines of Mexico were found to be quite variable in xylem 

monoterpene composition (Smith 1982a). Lockhart (1990a) found a large 

amount of either limonene or ß–phellandrene or both in nearly all trees in 

Nuevo Leon, Mexico, and found considerable range in composition throughout 

Mexico. Number of trees was not given, but large ranges in limonene and ß– 

phellandrene were reported. 

#30. P. griffithii x wind 

Source n α–p cam ß–p sab myr lim ß–ph ter 

TR 2 ------------------------------- percent: normalized 

85.6 2.1 7.2 1.8 1.4 0.8 0.3 1.0 

TR 1 84.9 4.2 2.6 3.5 1.8 0.7 0.4 2.0 

M - 88.0 - - - - - - -

The above format is explained in the introduction to this chapter. 

The composition of the two trees, labelled P. excelsa in the arboretum, was 

high α–pinene with small or trace amounts of camphene, ß–pinene, sabinene, 

myrcene, limonene, ß–phellandrene, and terpinolene; these small amounts 

were not found in the next item, #31, suggesting that the wind parents of these 

two trees were quite different from the P. griffithii male parent of #31. The 2:1 

ratio of sabinene to terpinolene was consistent with other pines. 

#31. P. griffithii x P. griffithii 

Source n α–p cam ß–p myr lim 

percent: normalized 

TR 3 98.8 0.2 0.4 0.3 0.3 

The above format is explained in the introduction to this chapter. 

All three trees were nearly identical with greater than 98 percent α–pinene 

and small to trace amounts of other monoterpenes. This suggests that some P. 

griffithii had a (1-1) set of alleles for α–pinene with no active alleles for any 

other monoterpene. The difference between #31 and #30 may be biosynthetic, 

and not genetic. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#32. Pinus halepensis x wind 

Source n α–p cam ß–p car myr lim ß–ph ter 

---------------------------- percent: normalized 

TR 15 67.4 0.5 11.5 15.1 1.4 1.4 0.6 1.8 

TR 6 76.6 0.2 7.0 11.7 1.5 0.6 0.5 1.0 

TR 1 40.8 0.3 22.1 23.8 2.6 - 1.0 4.3 

TR 1 81.6 0.5 7.4 7.6 2.0 - 0.9 * 

TR 1 59.0 * 1.6 32.6 1.2 3.7 - 1.9 

TR 1 98.4 * 0.5 0.2 0.8 - - -

M 97.0 - - - 2.0 - - -

1 472 82.3 - 1.9 2.5 7.2 0.4 3.4 -

1

Schiller and Grunwald 1987. 

The above format is explained in the introduction to this chapter. 

The first two sets of trees, numbering 15 and 6 and growing at IFG, were 

examined at different times. Both sets were quite similar in average composition 

and different than that reported by Mirov and others (1966) who found three 

widely separated sources to be about the same with approximately 95 percent 

α–pinene; only four such trees were found among the 21 examined here. The 

other 17 had appreciable amounts of either ß–pinene or 3-carene or both, which 

was more characteristic of P. brutia. Although 21 trees were hardly sufficient for 

an analysis of frequency distribution, there was a tendency for a multimodal 

distribution for α–pinene, ß–pinene, and 3-carene. A recent paper by Conkle 

and others (1988) gave data from isozyme analysis to fix P. brutia as a separate 

species from P. halepensis. Conkle and others base their conclusions partly on 

the prior work of Mirov and others (1966). It would appear that the species and 

varietal status of P. brutia and P. halepensis is not fully resolved. For this report 

P. brutia will be considered a separate species. 

Quite different results were also reported by Schiller and Grunwald (1987) 

who made a range-wide study of 472 7-year-old trees. By using a canonical 

discriminate analysis on individual monoterpenes, Schiller and Grunwald 

(1987) made a first-level division of P. halepensis into three geographic areas: N. 

Africa, Greece, and Spain; they also made second- and third-level divisions. 

Some support for the results of the canonical procedure was given by an 

analysis of types of composition, although the procedure for determining types 

of composition was not clear to me. 

#33. P. halepensis x P. brutia 

Source n α–p cam ß–p car myr lim ß–ph ter 

-----------------------------percent: normalized 

TR 5 80.4 0.2 2.9 11.3 1.1 2.4 0.5 1.3 

TR 1 58.1 0.3 4.5 24.3 2.0 7.3 1.1 2.4 

TR 1 97.0 0.2 1.3 - 0.6 0.7 0.1 

The above format is explained in the introduction to this chapter. 

The composition of the five trees examined had considerable variation in 

α–pinene, 3-carene, and limonene. This agreed with the report by Mirov and 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

others (1966) who reported the composition of P. halepensis to be nearly pure α– 

pinene, but that of P. brutia (see #4 above) to be quite variable in α-pinene, 

ß–pinene, and 3-carene. The five trees were quite similar in composition to the 

reciprocal trees in item #5 above. 

#34. Pinus jeffreyi 

Source n hep non α–p und cam ß–p car sab myr lim ß–ph ter 

----------------------------------- percent: normalized ------------------------

TR 18 97.5 * 0.3 0.1 0.2 0.2 * 0.5 * 1.1 -

M 1 96.0 

The above format is explained in the introduction to this chapter. 

These 18 trees were much like those reported elsewhere (Mirov 1961, Smith 

1971) and in Chapter 3 of this volume. Simply stated, the volatile portion of P. 

Jeffrey xylem resin was nearly all n-heptane, and there is little, if any, local or 

regional variation. It is difficult to explain the small amounts of monoterpenes. 

There were no appreciable amounts of monoterpenes from which isomers 

could be formed unless such a mechanism existed for heptane. See Chapter 3 of 

this volume for more detailed data on P. jeffreyi. 

#35. P. jeffreyi x P. coulteri** 

Source n hep non α–p cam ß–p car sab α–ph myr lim ß–ph 

percent: normalized -------------------------

TR 13 66.9 0.6 14.1 1.4 0.6 0.3 0.1 0.2 4.4 1.3 10.1 

TR 1 76.6 0.1 13.2 1.7 0.4 0.2 - - 1.4 0.6 5.4 

TR 1 50.7 1.9 11.6 1.9 0.1 - 0.2 - 5.7 10.5 17.5 

TR 1 58.5 1.3 23.9 1.3 0.9 * * 0.4 3.9 1.5 8.3 

TR 1 94.2 0.5 1.1 - - 0.2 - - 1.4 - 2.8 

The above format is explained in the introduction to this chapter. 

The average n-heptane, 67 percent, for these 13 trees was much higher than 

expected, even if intermediacy, about 45 percent, was postulated. The same 

reason given for this phenomenon for the cross with P. montezumae may apply 

here also; i.e., P. coulteri might have an active site for n-heptane, since P. coulteri 

often had small to trace amounts (see #13 above). The one tree with nearly pure 

heptane, 94 percent, could be rationalized as a result of self-pollination. The 

remaining 12 trees showed the effect of both parents. One would expect greater 

α–pinene and ß–phellandrene, since P coulteri brings more alleles to the cross, 

but this may be in the normal range of variation. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#36. P. jeffreyi x P. ponderosa** 

Source n hep non α–p cam ß–p car myr lim ß–ph ter 

---------------------------------- percent: normalized 

TR 7 38.3 0.2 7.8 0.6 30.9 15.5 3.1 1.0 2.1 0.2 

TR 1 52.8 0.4 4.0 0.3 16.2 25.2 0.5 - - * 

TR 1 34.2 0.3 8.2 1.2 34.0 3.3 4.6 1.5 12.7 * 

S 1 17.9 1.3 14.9 0 23.3 27.0 3.0 0.9 7.5 1.1 

S

Smith (1967a) also records 3.2 percent undecane. 

The above format is explained in the introduction to this chapter. 

The average composition for these seven trees showed the expected 

characteristics of both parents, but the amount of n-heptane was often much 

lower than the expected 45 percent, if intermediacy was postulated. This could 

have been caused by P. ponderosa having more active alleles for monoterpenes. 

(Thus, P. jeffreyi alleles do not have equal access to the terpene precursor.) The 

one tree with 12.7 percent ß–phellandrene was a bit puzzling since neither 

parent tree had a significant amount of ß–phellandrene. Again, this might 

indicate the action of a minor genetic system. The tree listed for Smith (1966b) 

was used in testing the resistance of the hybrid to western pine beetle attack. 

#37. P. jeffreyi x P. ponderosa var. scopulorum** 

Source n hep non α–p cam ß–p car myr lim ß–ph y-ter ter 

----------------------------------- percent: normalized 

TR 5 37.7 0.7 9.1 0.1 5.0 41.8 1.1 1.6 0.3 0.2 2.5 

TR 1 33.5 0.7 19.6 0.1 11.8 29.9 0.9 0.9 0.4 0.1 2.0 

TR 1 50.4 0.6 0.9 * 0.7 40.8 0.9 1.6 0.2 0.2 3.6 

S 1 29.0 1.0 4.0 1.0 1.0 57.0 2.0 1.0 1.0 * 4.0 

The above format is explained in the introduction to this chapter. 

These five progeny resembled those in the previous item #36. Again, the 

amount of n-heptane was generally lower than the expected 45 percent, if 

intermediacy was postulated, and one might speculate that P. ponderosa var. 

scopulorum had more sites that compete for the terpene precursor. The composition 

of one tree closely resembled that of a previous report (Smith 1967b). 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#38. P. jeffreyi x P. washoensis** 

Source n hep non α–p cam ß–p car myr lim ß–ph ter 

-------------------------------------- percent: normalized 

TR 3 48.6 0.9 6.0 0.4 5.1 26.1 5.8 0.1 5.7 1.3 

TR 1 35.7 0.3 7.9 0.4 1.6 42.4 9.8 * 0.1 1.9 

TR 1 15.3 2.2 9.2 1.0 13.6 35.4 6.3 0.4 14.5 2.0 

TR 1 94.8 0.2 0.9 - * 0.4 1.3 - 2.4 -

S 1 32.0 - 2.0 - 2.0 45.0 12.0 1.0 1.0 4.0 

The above format is explained in the introduction to this chapter. 

The average amount of n-heptane in the three progeny was misleading as 

shown by the three individually listed trees. The 95 percent heptane in one of 

the individually listed trees strongly suggests that this tree was P. jeffreyi, 

probably caused by selfing, and not a hybrid. By discounting the 95 percent 

tree, the average for heptane is far below the postulated intermediacy of about 

45 percent. Thus, crosses with P. washoensis were, as expected, similar to those 

with P. ponderosa var. scopulorum as noted in the previous item. The one tree 

with greater than expected amount of ß–phellandrene really looked like a 

hybrid of P. jeffreyi with P. coulteri. 

#39. P. jeffreyi x P. montezumae** 

Source n hep non α–p cam ß–p car myr lim ß–ph ter 

------------------------------------percent: normalized --------------------------

TR 1 77.7 6.3 4.5 0.2 8.5 7.2 0.8 - 0.1 0.5 

The above format is explained in the introduction to this chapter. 

Only one tree was examined for this cross, and the composition was not as 

expected, if intermediacy was postulated; i.e., one would expect much lower 

heptane, about 45 percent, and much greater α-pinene, about 45 percent, in this 

hybrid. Even if the P. montezumae parent had only active alleles for α–pinene, nheptane should not have been so high. An interesting possibility is that some 

varieties of P. montezumae might have moderate amounts of n-heptane. Could 

the P. montezumae parent have had an allele for heptane? Smith (1982a) found 

some variation in P. montezumae and its varieties, and high α–pinene and 

mixtures of α–pinene and ß–pinene. P. montezumae almost always had a small 

amount of nonane, about 2 to 5 percent (Smith 1982a), and this seems to be 

carried through to the F-1 generation, which will be noted for the P. ponderosa x 

P. montezumae hybrid (see #78 below). One might use this as possible evidence 

of a minor genetic system as well as a marker for P. montezumae. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

Figure 4-1—Frequency distribution (histogram) of heptane and ß–phellandrene in 

62 progeny of P. jeffreyi x P. jeffreyi.coulteri, 

and the modal analysis of the distribution; 

individual mode average (av.)( ▲ ) given as 

a full number in percent of composition, 

mode proportion (pr.) given as a decimal 

based on a sum of 1.0; analysis based on 

normal distribution; heavy line is best fit 

of the histogram; thin line is best fit of the 

modes. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#40. P. jeffreyi x P. jeffreyi.coulteri 

Source n hep non α–p und cam ß–p car sab α–ph myr lim ß–ph 

--------------------------------- percent: normalized 

TR 62 86.0 0.5 3.8 - 0.9 0.2 0.3 0.1 * 2.3 0.5 5.7 

TR 1 87.2 0.1 3.5 - 0.6 0.1 0.9 0.2 - 2.1 * 5.4 

TR 1 77.6 0.3 5.3 - 1.1 0.1 * 0.1 - 3.0 0.2 12.3 

TR 1 70.0 1.3 8.5 - 1.1 0.5 0.3 0.6 - 4.4 0.9 12.7 

TR 1 65.2 0.1 9.1 - 1.0 0.2 0.4 0.3 * 4.8 0.7 18.3 

TR 1 81.3 0.8 10.0 - 0.7 0.5 - 0.1 * 0.2 0.5 5.9 

TR 1 95.4 0.1 1.1 - 0.2 0.3 0.6 0.3 - 0.2 1.9 * 

S 1 72.0 1.0 12.0 * * 1.0 1.0 * - 2.0 1.0 11.0 

S 1 93.0 * 1.0 * 2.0 * * * - 1.0 * 3.0 

S 1 85.0 1.0 1.0 - 1.0 * * * - 6.0 * 5.0 

S 1 83.0 * 5.0 - 1.0 3.0 1.0 * - 3.0 * 4.0 

S

Smith (1967a), full siblings. 

The above format is explained in the introduction to this chapter. 

Heptane was generally high, as expected. There was considerable range in 

the amount of heptane, α–pinene, and ß–phellandrene. Myrcene, attributable 

to P. coulteri, had only a modest range and was lower than expected. All four 

components tended to have a multimodal frequency distribution as illustrated 

by heptane and ß–pinene (fig. 4-1), suggesting additive alleles for heptane and 

ß–phellandrene. Again, as for other hybrids, the one tree with near-pure 

heptane can be rationalized by accidental selfing of P. jeffreyi. Since the 

frequency distribution of both heptane and the monoterpenes tended to be 

multimodal, it might be concluded that they both draw on the same precursor. 

#41. P. jeffreyi.coulteri x wind 

Source n hep non α–p cam ß–p car sab myr lim ß–ph 

--------------------------------- percent: normalized ------------------------

TR 2 72.9 0.4 8.9 1.4 0.3 * 0.2 3.5 1.5 10.7 

TR 1 94.6 0.3 0.5 1.7 - 0.3 - 0.4 - 2.1 

TR 1 82.3 0.5 4.2 1.1 * - 0.2 2.7 0.6 8.4 

TR 1 75.3 1.5 3.8 4.1 0.1 - 0.1 0.3 0.6 14.2 

TR 1 64.5 0.7 12.0 1.3 0.1 - 0.2 5.5 0.9 15.0 

TR 1 43.5 0.1 27.2 0.9 0.5 - 0.1 6.8 6.8 14.1 

TR 1 17.9 2.8 27.3 2.8 - - 0.6 14.3 5.9 28.4 

The above format is explained in the introduction to this chapter. 

The amount of ß–phellandrene was quite similar to P. jeffreyi x coulteri. 

In fact, all trees were fairly similar to those of P. jeffreyi x coulteri (see #35 

above). One really cannot be sure of the source of the wind pollen. Since both 

sets of trees (this item and #40 above) are quite similar, the wind pollen could 

have been P. jeffreyi.coulteri. The considerable variation in composition was 

attributed to P. coulteri. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#42. P. jeffreyi.ponderosa x wind

Source n hep non α–p cam ß–p car myr lim ß–ph γ–ter ter 

-----------------------------------------percent: normalized----------------------------

TR 3 3.7 0.1 4.4 0.1 16.5 42.7 13.5 13.9 1.0 0.1 2.7 

TR 1 2.0 - 2.6 0.2 5.0 51.6 7.8 28.7 - 0.1 2.9 

TR 1 4.2 * 4.2 - 21.0 41.6 13.3 11.0 1.6 0.2 2.9 

The above format is explained in the introduction to this chapter. 

It was clear that "wind" was most likely P. ponderosa, since all trees had 

nearly the composition of P. ponderosa. The presence of measurable amounts of 

n-heptane again suggests additive alleles; if there was a dominant/recessive 

structure, one would expect either no heptane (two recessive) or an appreciable 

amount (dominant-recessive). The one tree with about 29 percent limonene 

was interesting because high limonene was rarely found in P. ponderosa (see 

Chapter 5). Here again, as in several other instances, the presence of a small 

amount of heptane raised the question of its source because one would expect 

either zero percent or an appreciable amount of about 15 to 20 percent. Could 

these small amounts be derived from low activity by a (0-0) set of additive 

alleles? Or is there a minor genetic system? 

#43. P. jeffreyi.ponderosa x P. engelmannii 

Source n hep non α–p cam ß–p car myr lim ß–ph ter 

percent: normalized 

TR 3 3.5 0.2 69.7 0.2 9.6 3.1 7.5 5.0 0.5 0.5 

TR 1 0.2 0.6 83.1 0.3 2.4 2.3 11.1 - - -

TR 1 9.4 * 79.9 * 0.6 2.0 7.5 - - 0.5 

The above format is explained in the introduction to this chapter. 

The composition of the three trees that had predominantly characteristics 

of P. engelmannii was a bit puzzling; the α–pinene was so much higher than 

expected and ß–pinene, 3-carene, and n-heptane were so much lower than 

expected. Although one might rationally explain the condition by having a (0-

0) pair of additive alleles for all the P. ponderosa genes— ß–pinene, 3-carene, 

myrcene, and limonene—in the P. ponderosa parent of the P. jeffreyi x P. ponderosa 

hybrid and a (1-1) pair of additive alleles for n-heptane in the P. jeffreyi parent, it 

seems unusual that the condition occurred for all four genes at the same time. 

There was no such tree in a total of 12 progeny of crosses of P. jeffreyi with P. 

ponderosa and with P. ponderosa var. scopulorum, #36 and #37 above. The reciprocal 

of this cross, #26, was not too similar in composition to #43. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#44. P. jeffreyi.ponderosa x P. jeffreyi 

Source n hep non α–p ß–p car myr lim ß–ph 

-------------------------------------- percent: normalized 

TR 8 78.4 1.3 1.9 0.8 8.0 4.2 2.6 0.1 2.8 

TR 1 81.1 0.3 2.5 0.8 11.7 2.2 1.4 - * 

TR 1 72.3 2.6 1.8 1.9 0.4 3.4 3.9 0.5 13.1 

TR 1 61.3 1.1 2.1 0.5 10.2 22.2 2.5 - -

TR 1 73.1 1.0 3.0 * 11.2 0.4 6.6 - 4.0 

S 95.0 * 3.0 * * 1.0 1.0 * * 

The above format is explained in the introduction to this chapter. 

The average composition of the eight trees showed, as expected, the strong 

characteristics of P. jeffreyi; yet there were still some effects of P. ponderosa with 

8 percent ß–pinene, 4 percent 3-carene, and 3 percent each for myrcene and ß– 

phellandrene. This again suggested that the cross produced some (0-0) alleles 

for ß–pinene and 3-carene, whereas, if it was a double recessive, there would be 

no ß–pinene or 3-carene. The 13 percent ß–phellandrene was unusual because 

neither parent species had more than 1 or 2 percent generally. However, a rare 

P. jeffreyi with 12 percent ß–phellandrene was reported for that species in 

Chapter 3; maybe such a tree was the male parent. Or there could have been an 

aggregate of several of the minor effects on monoterpene composition. 

#45. P. jeffreyi.ponderosa x P. ponderosa 

Source n hep non α–p cam ß–p car sab myr lim ß–ph ter 

------------------------------------ percent: normalized --------------------------

TR 8 3.9 0.1 7.6 * 10.9 45.8 * 13.4 15.7 0.4 1.8 

TR 1 0.4 - 9.8 - 1.7 59.0 * 8.2 19.1 * 2.0 

TR 1 2.1 - 10.0 0.1 20.5 33.3 - 15.8 14.7 * 2.1 

TR 1 23.0 1.2 7.5 * 15.8 29.7 * 12.7 9.8 * 0.6 

TR 1 1.0 - 6.0 - 10.4 49.7 * 11.8 17.6 1.7 0.8 

S 1 * 8.0 1.0 21.0 47.0 - 6.0 13.0 2.0 2.0 

S 1 4.0 1.0 10.0 * 21.0 39.0 - 7.0 15.0 1.0 3.0 

The above format is explained in the introduction to this chapter. 

In this cross the characteristics of P. jeffreyi were essentially lost because 

only one of the trees had an appreciable amount of n-heptane. All seven other 

trees were essentially like P. ponderosa. The two trees listed from Smith (1967a) 

were full siblings and show a strong similarity to the eight trees of this report. 

The relationship of biosynthesis between monoterpenes and heptane was not 

clear. No reciprocals of this cross were in the arboretum. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#46. [P. jeffreyi x (jeffreyi.coulteri)] x P. ponderosa 

Source n hep non α–p und cam ß–p car sab myr lim ß–ph ter 

-----------------------------------percent: normalized 

TR 6 11.8 0.3 7.0 0.2 17.5 31.0 6.4 11.1 13.3 1.4 

TR 1 1.0 0.3 8.6 0.3 18.3 31.0 11.8 8.0 19.8 2.2 

TR 1 23.4 0.6 7.3 0.1 18.3 20.7 6.5 9.8 12.4 0.9 

TR 1 10.0 0.3 8.6 0.3 16.3 27.0 11.8 7.0 16.8 2.2 

TR 1 14.7 0.6 6.2 - - 22.9 6.7 24.2 22.4 2.6 

S 1 * * 11.0 2.0 * 27.0 26.0 * 3.0 14.0 16.0 4.0 

The above format is explained in the introduction to this chapter. 

The female parent was a naturally occurring backcross of P. jeffreyi.coulteri 

to P. jeffreyi (Zobel 1952). The average of the six trees showed characteristics of 

all three parents: heptane of P. jeffreyi; ß–pinene, 3-carene, of P. ponderosa; ß– 

phellandrene of P. coulteri; and limonene and myrcene of both P. coulteri and P. 

ponderosa. The one tree examined in 1967 had only a trace of heptane, but only 

one tree with only a trace of heptane was found in this six-tree sample. 

All trees of this cross had a very poor and very slow flow of resin, a 

characteristic not unusual for many other interspecific crosses. On the other 

hand, the flow of resin from all three parent species was usually very good. 

#47. [P. jeffreyi x jeffreyi. coulteri] x P. jeffreyi.ponderosa 

Source n hep non α–p und cam ß–p car sab myr lim ß–ph 

-----------------------------------percent: normalized 

TR 10 45.0 1.1 10.1 0.3 9.1 3.1 * 8.5 2.2 20.3 

TR 1 78.4 1.7 5.7 0.3 0.6 - 7.0 * 6.2 

TR 1 39.2 0.1 3.9 0.4 * * 11.6 * 45.1 

TR 1 98.6 0.1 0.4 * 0.2 - 0.3 - 0.4 

TR 1 25.3 2.7 6.0 * 11.4 24.8 * 9.8 6.1 12.6 

S 1 20.0 1.0 12.0 1.0 - 40.0 5.0 * 2.0 8.0 12.0 

The above format is explained in the introduction to this chapter. 

The female was the same type as #46 above. The 10 trees examined had a 

great range in heptane, α–pinene, ß–pinene, 3-carene, myrcene, limonene, and 

ß–phellandrene, thus reflecting all three parent species. There were some 

unusual compositions for individual trees; for example, one with 78 percent 

heptane looked like P. jeffreyi x Jeffreyi.coulteri, another with 16 percent myrcene 

and 51 percent ß–phellandrene looked like P. coulteri, and another with 14 

percent ß–pinene, 54 percent 3-carene, and 6 percent limonene looked 

somewhat like P. ponderosa. The small amount of heptane in some trees seemed 

puzzling, because both hybrid parents contain P. jeffreyi, but a (0-1) set of 

additive alleles for heptane in both parents was possible and could explain the 

small amount of heptane in some of these progeny. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#48. Pinus longifolia

Source n α–p cam ß–p car sab myr lim ß–ph γ–ter ter 

------------------------------------percent: normalized 

TR 2 15.8 0.1 9.7 64.2 * 3.3 0.6 0.7 0.4 5.4 

TR 1 19.2 * 15.9 54.6 - 3.7 1.1 0.9 0.3 4.2 

S 1 18.0 - 18.0 56.0 - 3.0 1.0 1.0 * 4.0 

M 1 24.0 10.0 38.0 - - - - - -

The above format is explained in the introduction to this chapter. 

Only two trees were examined, and the average composition as well as the 

individual compositions were reasonably similar to that reported earlier (Mirov 

1961, Smith 1967a). This species is now known as P. roxburghii. 

#49. Pinus monticola 

Source n hep α–p und cam ß–p car sab myr lim ß–ph ter 

---------------------------------- percent: normalized 

TR 12 53.6 0.7 22.1 7.7 5.7 3.1 1.5 3.6 1.8 

TR 1 18.8 0.4 36.8 - 18.8 1.0 0.9 17.3 6.0 

TR 1 77.8 * 15.6 - - 5.8 0.5 0.2 -

TR 1 30.9 0.1 40.2 - - 11.4 10.0 1.8 -

TR 1 19.1 * 23.9 48.8 - 4.6 * 1.0 2.6 

TR 1 65.8 1.3 7.0 - 15.7 1.0 0.6 4.1 4.6 

M 60.0 2.0 26.0 - - - - - -

The above format is explained in the introduction to this chapter. 

The average composition of 12 trees examined showed this species to be 

another of the α–pinene, ß–pinene types, as also shown by Mirov (1961). 

However, the individual trees had a wide range in several other components. 

The proportions of 3-carene and sabinene to terpinolene were illustrated in the 

five individual trees listed: the two without both components had no 

terpinolene; the one with 3-carene and no sabinene had about a 20:1 ratio of 3-

carene to terpinolene; and the ones with sabinene and without 3-carene had a 

ratio of about 3:1 of sabinene to terpinolene. See Chapter 3, #12, for more data 

on P. monticola. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#50. P. monticola x P. monticola 

Source n α–p und cam ß–p car sab myr lim ß–ph γ–ter ter 

----------------------------------- percent: normalized 

TR 8 61.7 2.4 22.2 * 4.8 2.6 4.3 1.2 0.1 0.8 

TR 1 49.7 3.1 25.2 * 2.3 6.6 10.1 1.3 0.9 0.9 

TR 1 80.0 3.4 8.0 - - 2.9 3.4 2.7 - -

S 1 81.0 - 4.0 12.0 - - 1.0 1.0 * - -

The above format is explained in the introduction to this chapter. 

The composition of these eight trees closely resembled those of the previous 

item #49. The only difference between them was that #49 was wind-pollinated 

seed, whereas item #50 was control-pollinated. 

#51. P. monticola x wind 

Source n α–p and ß–p car sab myr lim ß–ph γ–ter ter 

-----------------------------------percent: normalized 

TR 22 55.8 3.6 28.7 5.4 * 1.2 3.9 0.9 * 0.2 

TR 1 55.7 2.1 31.0 * - 0.6 9.8 0.8 - -

TR 1 50.0 2.1 15.0 30.0 - 0.7 0.4 1.0 - 0.9 

TR 1 92.4 - 6.6 - - 0.7 0.1 0.2 - -

TR 1 44.4 11.1 5.6 33.3 - 5.6 - - - * 

The above format is explained in the introduction to this chapter. 

These 22 trees were designated as wind pollinated and were similar to 

items #49 and 50 above, P. monticola and P. monticola x P. monticola. The 

designation depends on where and how the parents were when they were 

pollinated. It was interesting that no tree in this set of 22 had a measurable 

amount of sabinene, yet in a much smaller sample of 11 trees, #50 above, two 

trees had considerable amounts of sabinene. The data on natural stands of P. 

monticola (Chapter 3, #12) showed large local and regional variation in α– 

pinene, ß–pinene, 3-carene, and myrcene, and there was even appreciable 

variation in minor components: undecane, ß–phellandrene, sabinene, and 

nonane. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#52. P. monticola x P. strobus** 

Source n α–p and cam ß–p car sab myr lim ß–ph ter 

--------------------------------- percent: normalized --------------------------

TR 41 60.6 1.4 * 31.8 2.8 0.4 1.1 1.2 0.6 0.4 

TR 1 54.6 * * 36.9 3.1 - 4.3 0.4 0.7 -

TR 1 66.7 0.2 * 28.7 - 1.6 0.3 0.1 0.1 2.4 

TR 1 86.6 * * 12.9 - - 0.2 0.3 * -

TR 1 72.7 3.5 * 7.8 * 1.7 5.2 8.0 0.7 0.5 

TR 1 56.3 3.0 * 7.0 27.1 - 2.2 2.1 0.2 2.2 

TR 1 71.3 1.6 23.5 2.8 - 0.7 0.5 0.3 0.3 

TR 1 41.4 1.9 50.4 - - 0.7 3.9 1.6 -

S 1 52.0 - 3.0 43.0 - - 1.0 * * -

S 1 52.0 1.0 1.0 41.0 - - 1.0 1.0 1.0 -

M 73.0 - -.0 15.0 

The above format is explained in the introduction to this chapter. 

Mirov (1961) reported 75 percent α–pinene and 15 percent ß–pinene for P. 

strobus. The average of these 41 trees was just about intermediate between P. 

monticola and P. strobus, in a general sense. This hybrid also showed additional 

characteristics of P. monticola: 3-carene, sabinene, and limonene. There was a 

tendency for a trimodal distribution of both α–pinene and ß–pinene in this 

hybrid, suggesting additive alleles. 

#53. P. monticola x P. peuce** 

Source n non α–p cam ß–p car myr lim ß–ph ter 

----------------------- percent: normalized 

S 1 * 67.0 2.0 28.0 - 1.0 1.0 1.0 -

The above format is explained in the introduction to this chapter. 

This one hybrid was approximately intermediate to both parents. Mirov 

(1961) reports P. peuce with 50 percent α–pinene, 6 percent ß–pinene, 2 percent 

myrcene, and 1 percent terpinolene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#54. P. monticola x P. griffithii 

Source n non α–p und cam ß–p car sab myr lim ß–ph ter 

----------------------------------percent: normalized 

TR 19 81.7 1.6 - 14.3 0.9 - 0.5 0.3 0.2 * 

TR 1 97.8 0.3 - 0.4 - - 0.8 0.6 - -

TR 1 74.5 1.6 - 23.8 - - * 0.1 * -

TR 1 34.4 0.4 - 54.6 8.6 - 1.0 0.2 0.3 -

S 1 61.0 5.0 * 31.0 4.0 - * * * * 

The above format is explained in the introduction to this chapter. 

The average composition of these 19 trees was much higher in α–pinene 

than P. monticola x P. strobus, #52, and this was an expression of the higher α– 

pinene in P. griffithii. Mirov (1961) reported 90 percent α–pinene in P. griffithii, 

whereas in #30 and #31 (above) α–pinene was 85 percent and 98 percent. None 

of these 19 trees had any sabinene, and only one had a measurable amount of 3-

carene. Apparently none of the female P. monticola had any sabinene or 

3-carene; both components are fairly common in P. monticola (see Chapter 3). 

It appeared that individual trees of both parent species had a (1-1) set of 

additive alleles for α–pinene. 

#55. P. monticola x P. peuce. strobus 

Source n non α–p cam ß–p car myr lim ß–ph 

-------------------------------percent: normalized 

S 1 * 52.0 3.0 42.0 1.0 * * 1.0 

The above format is explained in the introduction to this chapter. 

This single 3-way hybrid had about the expected composition of largely α– 

pinene and ß–pinene with small or trace amounts of other monoterpenes. 

#56. Pinus muricata 

Source n α–p α–th cam ß–p sab myr lim ß–ph γ–ter ter 

-------------------------------- percent: normalized 

TR 9 35.0 1.0 0.3 2.4 37.1 1.1 0.4 1.0 0.4 21.2 

TR 1 5.2 3.0 1.0 1.4 56.7 * 0.7 0.3 31.8 

TR 1 95.0 0.2 - 2.7 - 1.1 - 0.9 - -

TR 1 43.1 * 0.2 3.7 29.3 1.3 * 1.8 0.5 20.1 

M - 98.0 - - - - - - - - -

The above format is explained in the introduction to this chapter. 

The composition of this species was given because it was used with P. 

attenuata in item #3 above. These few trees again showed the great variation of 

composition in P. muricata. See Chapter 3, #13, for more data on P. muricata. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#57. Pinus nigra x P. nigra

Source n α–p cam ß–p myr lim ß–ph 

----------------------------- percent: normalized 

TR 5 86.9 0.6 2.0 1.0 9.3 0.2 

TR 1 92.7 0.5 1.8 1.0 3.4 0.7 

TR 1 74.6 0.3 1.4 2.0 21.6 

M 1 94.0 - -

The above format is explained in the introduction to this chapter. 

The average composition of these five trees, like all others of P. nigra and its 

varieties, was about 90 percent α–pinene and small to trace amounts of other 

monoterpenes. However, one tree had more than 22 percent limonene and 75 

percent α–pinene, which was unusual. The only other hybrid with P. nigra that 

contained modest amounts of limonene was P. nigra x P. resinosa, item #67 

below. Did this modest amount of limonene, listed here, reflect variation in P. 

nigra or was it a rogue and likely the progeny of P. nigra x P. resinosa? Hybrid 

#64 could be such a tree. The results suggest that P. nigra and its varieties have 

a (1-1) set of additive alleles for α–pinene. 

#58. P. nigra var. calabrica x wind 

Source n α–p cam ß–p myr lim ß–ph 

TR 2 

--------------------------- percent: normalized 

94.4 0.5 2.9 0.8 0.7 0.6 

The above format is explained in the introduction to this chapter. 

Only two trees of P. nigra var. calabrica were sampled, and both were nearly 

pure α–pinene at 94 percent; ß–pinene was about 3 percent, and the remainder 

was small amounts of camphene, myrcene, limonene, and ß–phellandrene. 

P. calabrica was once a separate species, but it is now considered a variety of 

P. nigra. The varietal status of P. nigra probably is not fully resolved. 

#S9. P. nigra var. calabrica x P. nigra 

Source n α–p cam ß–p myr lim ß–ph 

-------------------------------percent: normalized ------------------

TR 3 92.2 0.7 2.2 1.3 3.0 0.7 

S 1 92.0 3.0 3.0 1.0 1.0 -

The above format is explained in the introduction to this chapter. 

All three trees were quite similar. Smith (1967a) found much the same 

except for small differences in the minor components. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#60. P. nigra.calabrica x wind 

Source n α–p cam ß–p myr lim ß–ph 

---------------------------- percent: normalized 

TR 1 94.6 0.9 2.0 1.0 1.3 0.2 

The above format is explained in the introduction to this chapter. 

The composition of this one tree was about 95 percent α–pinene with small 

to trace amounts of other monoterpenes. As will be shown in the subsequent 

various intra specific hybrids and by item #58 (var. calabrica), all varieties of P. 

nigra had about the same composition, except as noted for one tree in item #57 

above. 

#61. P. nigra var. calabrica x P. var. calabrica 

Source n α–p cam ß–p sab myr lim ß–ph 

-----------------------------------percent: normalized ---------------------------

TR 4 94.9 0.8 1.4 * 0.9 1.9 0.2 

S 1 94.0 1.0 3.0 * 1.0 1.0 * 

S 1 92.0 3.0 3.0 * 1.0 1.0 * 

The above format is explained in the introduction to this chapter. 

The composition of the four trees was essentially like others of P. nigra and 

its intraspecific hybrids, with 92 to 95 percent α–pinene and small to trace 

amounts of other monoterpenes. 

#62. P. nigra var. calabrica x P. longifolia 

Source n α–p cam ß–p car sab myr lim ß–ph γ–ter ter 

-------------------------percent: normalized ---------------------------

TR 3 96.8 * 2.7 * * 0.1 0.3 - 0.4 -

TR 1 96.4 * 3.4 - - 0.1 0.1 - - -

TR 1 98.6 - 1.4 - - - - - - -

The above format is explained in the introduction to this chapter. 

All three trees sampled had about the same composition, about 97 percent 

α–pinene, 3 percent ß–pinene, and trace amounts of camphene, myrcene, and 

limonene. To achieve this composition, the male parent, P. longifolia, must have 

been near-pure α–pinene; however, because the P. longifolia reported earlier, 

#48, were high 3-carene and not high α–pinene, one might suspect that the 

three trees sampled were products of selfing of P. calabrica. The alternative was 

that there were P. longifolia with near-pure α–pinene without 3-carene, but such 

has not been reported. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#63. P. nigra var. calabrica x P. thunbergiana 

Source n α–p cam ß–p myr lim ß–ph 

TR 5 -------------------------------percent: normalized 

91.7 0.8 3.5 1.1 1.3 1.6 

TR 1 93.3 0.8 3.9 1.0 0.9 

TR 1 88.1 0.8 3.6 1.3 2.3 4.0 

The above format is explained in the introduction to this chapter. 

The composition of these five hybrids was nearly identical to those of other 

intervarietal crosses of P. nigra. The one tree with 4 percent ß–phellandrene 

suggested that P. thunbergiana might have a (0-1) or (1-1) set of additive alleles 

for ß–phellandrene. Mirov (1961) lists P. thunbergiana as 83 percent α–pinene 

and 10 percent ß–pinene, but no ß–phellandrene. As noted earlier, the 4 percent 

ß–phellandrene could result from the aggregate of a number of small minor 

effects. Or the sampling of natural trees of P. thunbergiana was inadequate. P. 

thunbergiana was once known as thunbergii. 

#64. P. nigra x P. resinosa** 

Source n α–p cam ß–p myr lim ß–ph 

----------------------------- percent: normalized ------------------

TR 4 78.0 0.5 10.3 0.6 8.7 2.0 

TR 1 73.4 0.4 17.3 0.8 6.3 1.8 

TR 1 80.6 0.5 2.3 0.1 14.5 2.1 

The above format is explained in the introduction to this chapter. 

These four hybrids suggested that P. resinosa had genes for α–pinene, ß– 

pinene, and limonene. Mirov (1961) reported 92 percent α–pinene and 3 percent 

ß–phellandrene. The one tree with 14.5 percent limonene resembles one listed as 

P. nigra x P. nigra in #57. 

#65. P. nigra var. cebenensis x wind 

Source n α–p cam ß–p car myr lim ß–ph 

--------------------------------- percent: normalized ---------------------------

TR 11 95.6 0.7 1.4 * 0.9 1.0 0.4 

The above format is explained in the introduction to this chapter. 

These 11 trees were also varieties of P. nigra. Their average composition 

was nearly identical to varieties of P. nigra and of P. nigra var. calabrica. This 

limited analysis of intraspecific hybrids of P. nigra suggested that all varieties 

were near-pure α–pinene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#66. P. nigra var. cebenensis x wind 

Source n α–p cam ß–p car myr lim ß–ph 

------------------------------------- percent: normalized 

TR 2 94.8 0.8 1.4 0.2 0.9 1.3 0.5 

The above format is explained in the introduction to this chapter. 

The two trees were about 95 percent α–pinene with small or trace amounts 

of camphene, ß–pinene, myrcene, limonene, and ß–phellandrene. Thus, they 

were the same as other varieties of P. nigra. 

#67. P. nigra var. cebenensis x P. nigra 

Source n α–p cam ß–p myr lim ß–ph 

--------------------------- percent: normalized --------------------

TR 5 94.8 0.8 1.7 0.9 1.6 0.3 

S 1 92.0 2.0 2.0 1.0 2.0 * 

The above format is explained in the introduction to this chapter. 

P. nigra has had at times several varieties, cebenensis being one of them. 

These five trees are thus intraspecific hybrids. Their average composition was 

essentially 95 percent α–pinene, with small to trace amounts of several other 

monoterpenes. 

#68. P. nigra var. cebenensis x P. nigra var. cebenensis 

Source n α–p cam ß–p myr lim ß–ph 

--------------------------- percent: normalized 

TR 4 93.2 1.6 2.3 1. 1.8 0.2 

0 S 1 95.0 2.0 2.0 1.0 1.0 -

The above format is explained in the introduction to this chapter. 

The composition of these four intraspecific hybrids plus that of the one tree 

reported earlier were nearly the same, about 94 percent α-pinene and small to 

trace amounts of five other monoterpenes. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#69. Pinus patula x wind

Source n α–p cam ß–p car α–ph myr lim ß–ph ter 

-------------------------------------- percent: normalized 

TR 1 6.7 0.5 0.5 0.6 1.0 1.5 2.1 87.0 0.2 

M 5.0 - - - - - - 75.0 -

1 1 15.0 - 2.0 18.0 - - - 37.0 1.5 

1

Lockhart (1990b) (Lockhart's analyses also included 13 percent sesquiterpene) 

The above format is explained in the introduction to this chapter. 

This one tree was similar to that reported by Mirov (1961) who found 5 

percent α–pinene, 75 percent ß–phellandrene, and 10-15 percent sesquiterpenes. 

P. patula apparently had a (1-1) set of additive alleles for ß–phellandrene. 

Lockhart (1990b) found a wide range in composition in Central America stands, 

including high ß–phellandrene like the ones above. Average values given are 

derived from a diagram and not a table. Lockhart's data showed the number of 

trees with a large amount of a given component and gave individual tree 

composition in bar graph form for only 21 trees. Nevertheless, trees in every 

Central American country seemed to have a different composition: either high 

α–pinene, or high 3-carene, or high limonene, or high ß–phellandrene, or 

combinations of these four. From the data given by Lockhart, P. patula was 

extremely variable like P. muricata, P. ponderosa, and P. lambertiana. 

#70. P. patula x P. greggii** 

Source n α–p cam ß–p car α–ph myr lim ß–ph ter 

--------------------------------- percent: normalized -------------------

TR 13 35.8 0.2 0.5 17.2 0.2 16.9 0.7 27.4 0.8 

TR 1 22.8 - 0.6 15.3 * 40.5 * 19.5 0.1 

TR 1 46.3 0.4 0.4 14.2 0.3 1.2 1.1 34.8 1.2 

The above format is explained in the introduction to this chapter. 

These 13 trees were an interesting study in that six of the trees were very 

similar in composition and are illustrated by the first single tree listed, whereas 

the other seven were quite different than the first set and were like the second 

tree listed. Thus, the two distinct types of composition are quite different from 

each other. Mirov (1961) was not clear on P. greggi (see item #33 above). He 

simply lists a large amount of α–pinene and ß–pinene. A large portion of his 

sample was unresolved, although he does speculate that the unresolved portion 

might be ß–phellandrene and/or limonene. Neither P. patula nor P. greggii (#69 

and #29 above) listed in this report had a large amount of α–pinene, yet all 

hybrids listed here had a moderate amount of α–pinene. Therefore, the 

sampling of both species was not complete until Lockhart (1990b) found a large 

amount of α–pinene in P. patula. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#71. Pinus pinaster x wind

Source n α–p cam ß–p myr lim ß–ph sab 

----------------------------------percent: normalized 

TR 2 52.5 0.4 41.7 0.5 4.0 1.0 -

M - 63.0 - 27.0 - - - -

1 85.0 * 11.0 - 2.0 - 2.0 

1

Montioliva and others 1969. 

The above format is explained in the introduction to this chapter. 

These two trees had near-equal amounts of α–pinene and ß–pinene and 

small or trace amounts of camphene, myrcene, limonene, and ß–phellandrene. 

Monteoliva and others (1969), in an intensive and extensive study reported 65 

to 87 percent α–pinene, 0 to 3 percent camphene, 11 to 20 percent ß–pinene, 2 to 

5 percent sabinene, and 1 to 8 percent limonene. They did not list terpinolene, 

although one would expect it because of the amounts of sabinene. Neither 

sabinene nor terpinolene was found in the two listed trees. The composition of 

P. pinaster was quite variable. 

#72. P. pinaster x P. pinaster 

Source n α–p cam ß–p myr lim ß–ph 

---------------------------percent: normalized 

TR 2 79.5 0.2 18.2 0.6 1.2 0.4 

TR 1 95.9 0.1 2.8 * 1.2 * 

TR 1 63.1 0.2 33.6 1.1 1.2 0.8 

The above format is explained in the introduction to this chapter. 

These two indicate a wide range in ß–pinene and α–pinene, which was not 

shown in item #71. The range of these two trees was more like that given by 

Monteoliva and others (1969). However, sabinene, limonene, and 3-carene still 

did not occur in appreciable amounts, as one might expect from the report by 

Monteoliva and others (1969). One might speculate that P. pinaster was variable 

in monoterpenes and that the limited breeding failed to use trees with moderate 

amounts of camphene, sabinene, and limonene as noted by Monteoliva and 

others (1969). Another possibility might be that P. pinaster was variable in 

composition but that the limited breeding failed to use trees with moderate 

camphene, sabinene, and limonene. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#73. Pinus ponderosa 

Source n α–p cam ß–p car myr lim ß–ph γ–.ter ter 

---------------------------------percent: normalized 

TR 151 7.6 0.1 31.6 36.7 10.0 11.9 1.0 1.7 

TR 1 0.1 - 36.9 30.0 12.4 9.0 - - 1.5 

TR 1 7.8 - 18.0 48.0 13.3 5.9 1.0 - 5.1 

TR 1 10.3 - 52.5 - 21.4 14.0 1.9 - -

TR 1 7.0 0.1 33.5 25.6 5.7 24.5 2.3 - 1.3 

TR 1 10.6 * 55.1 - 12.7 21.5 * - -

TR 1 9.7 0.1 22.7 56.5 9.2 0.6 * - 1.2 

TR 1 5.1 0.6 9.0 48.3 12.0 21.0 1.3 - 2.8 

TR 1 37.0 0.1 32.8 - 5.0 21.2 2.4 - -

TR 1 15.6 - 36.5 24.1 20.6 * 1.6 - 1.5 

S 1 5.0 - 15.0 51.0 9.0 16.0 1.0 * 3.0 

S 1 6.0 23.0 43.0 5.0 20.0 1.0 * 2.0 

The above format is explained in the introduction to this chapter. 

The average of these 151 trees and the selection of individual compositions 

were listed because the trees are in the arboretum and readily available for 

study. The central Sierra Nevada was the source of most of them; those listed 

were fairly representative of trees found in the Sierra Pacific region. Five other 

sections of this report give a more thorough treatment of P. ponderosa, and its varieties 

in Chapters 3, 5, 6, 7, and 8. In all the 20 species or hybrids that follow where P. 

ponderosa was given without a variety designation, it was most likely P. ponderosa var. 

ponderosa; the other two varieties were var. scopulorum and var. arizonica. 

#74. P. ponderosa x P. ponderosa var. scopulorum 

Source n α–p cam ß–p car myr lim ß–ph ter 

------------------------percent: normalized 

TR 45 14.7 0.2 22.4 45.0 9.4 9.3 0.8 1.7 

TR 1 28.2 * 31.5 25.7 6.8 5.9 1.2 0.5 

TR 1 16.4 * 15.3 52.6 6.1 8.2 - 1.2 

TR 1 6.8 - 25.6 45.7 7.1 12.0 * 2.9 

TR 1 5.8 0.9 15.9 56.9 17.1 * 0.7 2.5 

S 1 5.0 * 27.0 50.0 7.0 7.0 1.0 4.0 

S 1 28.0 1.0 33.0 29.0 3.0 7.0 1.0 2.0 

S 1 32.0 1.0 26.0 26.0 6.0 6.0 2.0 2.0 

S 1 35.0 1.0 28.0 24.0 2.0 8.0 1.0 1.0 

S

Smith (1967a) full siblings. 

The above format is explained in the introduction to this chapter. 

The average composition of the 45 trees, as well as the range of the 

individually listed trees, was very much like that of the reciprocal cross (item 

#83). The earlier report (Smith 1967a) listed individual trees with much less 3-

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

carene and somewhat higher α–pinene. Both α–pinene and ß–pinene tended 

toward a trimodal frequency distribution as illustrated by α–pinene (fig. 4-2). 

P. ponderosa var. scopulorum, as traditionally described, did not come out clearly 

as a definitive variety based on xylem monoterpenes; instead, types of 

composition found in the region assigned to var. scopulorum were found in 

regions assigned to the other varieties, and vice versa. 

#75. P. ponderosa x P. ponderosa var. arizonica** 

Source n α–p cam ß–p car sab myr lim ß– γ–ter ter 

ph 

---------------------------------- percent: normalized 

TR 24 30.1 0.2 25.4 28.1 0.7 5.9 7.0 0.7 * 1.7 

TR 1 19.3 - 27.8 30.7 - 9.0 11.6 * - 1.7 

TR 1 56.5 0.5 36.8 - - 1.4 3.8 1.0 - -

TR 1 47.1 0.2 6.1 35.3 - 7.8 * 0.7 0.1 2.9 

TR 1 23.6 0.4 37.4 - 16.8 3.2 5.6 1.2 - 11.8 

The above format is explained in the introduction to this chapter. 

The average of these 24 trees did not closely resemble the previous item 

#74, though some of the individual trees were quite similar, thus suggesting a 

difference between var. arizonica and var. scopulorum. The much greater α– 

pinene and lesser ß–pinene, limonene, and 3-carene than in the previous 

intraspecific hybrid were as expected. Peloquin (1984) suggested that var 

arizonica and P. engelmannii were introgressive in southern Arizona. Many 

individual trees of var. arizonica and P. engelmannii had the same composition. 

As with var. scopulorum, var. arizonica as traditionally described did not come 

out clearly as a definitive var. of P. ponderosa. This result was based on xylem 

monoterpene composition. The results for var. scopulorum were very similar for 

the same reason. 

178 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

Figure 4-2—Frequency distribution 

(histogram) of a-pinene in 45 progeny 

of P. ponderosa x P ponderosa var. scopulorum, and the modal analysis of the 

distribution; individual mode average 

(av.)( ▲ ) given as a full number in percent of composition, mode proportion 

(pr.) as a decimal based on a sum of 

1.0; analysis based on normal distribution; heavy line is best fit of the histogram; thin line is best fit of the 

modes. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 179 
Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#76. P. ponderosa x P. engelmannii** 

Source n α–p cam ß–p car myr lim ß–ph ter 

-------------------------------------- percent: normalized ------------------------------

TR 58 32.9 0.2 19.4 26.7 6.7 11.7 0.7 1.5 

TR 1 36.3 - 13.2 30.5 5.3 12.3 * 2.5 

TR 1 19.1 0.3 24.2 35.3 3.7 14.5 1.5 1.5 

TR 1 34.4 - 21.6 30.6 11.4 * - 1.8 

TR 1 47.4 - 19.1 - 8.0 25.0 - 0.4 

TR 1 60.2 * 24.7 - 9.9 5.5 * -

TR 1 8.8 0.6 33.2 42.4 6.0 6.2 * 2.6 

TR 1 40.9 * 2.5 32.3 6.7 15.4 - 2.1 

S 1 40.0 * .14.0 36.0 4.0 4.0 1.0 2.0 

S 1 40.0 * 18.0 25.0 4.0 10.0 1.0 1.0 

S 1 29.0 * 28.0 29.0 4.0 5.0 1.0 2.0 

S 1 32.0 1.0 17.0 34.0 6.0 7.0 1.0 3.0 

S

Smith (1967a) half-siblings 

The above format is explained in the introduction to this chapter. 

These 58 trees showed the effect of both parent species with high α–pinene 

from P. engelmannii, and ß–pinene, 3-carene, myrcene, and limonene from P. 

ponderosa. The average composition was very similar to the previous hybrid 

(#75 above); this was to be expected since var. arizonica and P. engelmannii had 

similar compositions. As suggested earlier for item #21 above, P. engelmannii 

apparently had a (1-1) set of additive alleles for α–pinene because there was 

always an intermediate amount of α–pinene, mostly between 20 percent and 50 

percent, in the hybrids. Two trees were the exception, having about 8 percent as 

illustrated by one of the listed trees (8.8 percent). The lack of high α–pinene in 

any of the hybrids suggested: (1) that the P. ponderosa parent had a (0-0) set of 

additive alleles for α–pinene and, therefore, there was no (1-1) set of alleles for 

α–pinene in the 58 hybrids; or (2) that the presence of alleles for three to four 

other components competing for the precursor, such as ß–pinene, 3-carene, and 

limonene, would prevent the full expression of the (1-1) set of alleles for α– 

pinene. This is highly unlikely. 

There was a distinct tendency for the frequency distribution of the major 

monoterpenes to be trimodal, as illustrated by α–pinene and ß–pinene (fig. 4-

3), providing more evidence for an additive alleles hypothesis. 

180 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

Figure 4-3—Frequency distribution 

(histogram) of α–pinene and ß– 

pinene in 52 progeny of P. ponderosa 

x P. engelmannii, and the modal of the 

distribution; x = percent, y = number; individual mode average (av.)(▲) 

given as a full number in percent of 

composition, mode proportion as a 

decimal based on a sum of 1.0; analysis based on normal distribution; 

heavy line is best fit of the histogram, 

thin line is best fit of the modes. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#77. P. ponderosa x P. washoensis 

Source n α–p cam ß–p car myr lim ß–ph ter 

------------------------------ percent: normalized 

TR 2 10.2 0.1 29.6 38.7 18.6 1.6 * 1.5 

S 1 11.0 - 40.0 26.0 11.0 9.0 1.0 2.0 

The above format is explained in the introduction to this chapter. 

These two trees were about as expected, because the composition of some 

individual P. ponderosa was somewhat the same as that of P. washoensis. 

Critchfield (1984) gives evidence that P. washoensis was very closely related to 

P. ponderosa, particularly var. scopulorum. Haller (1961) suggested that P. 

washoensis was more widely distributed than originally thought. The average 

composition was quite similar to the reciprocal cross, item #112 below (see 

Chapter 3, #19, for more data on P. washoensis). 

#78. P. ponderosa x P. montezumae** 

Source n hep non α–p und cam ß–p car myr lim ß–ph ter 

----------------------------------- percent: normalized 

TR 29 0.5 3.7 25.8 1.2 0.1 15.3 39.1 7.3 4.0 0.7 * 2.1 

TR 1 * 3.5 33.2 * * 9.6 40.2 6.2 6.9 0.3 0.1 

TR 1 * 4.3 22.0 5.1 - 20.9 34.5 10.8 - 0.6 2.1 

TR 1 - 3.0 21.4 - 0.8 2.3 47.9 16.0 3.9 1.2 * 3.3 

TR 1 - 4.5 47.1 - - 0.2 49.0 2.9 * 0.2 * 1.0 

TR 1 13.6 3.2 11.3 - * 13.0 47.1 4.8 3.7 0.6 * 2.4 

TR 1 5.0 5.0 41.0 3.0 - 26.0 - 4.0 16.0 1.0 -

The above format is explained in the introduction to this chapter. 

Both P. ponderosa and P. montezumae had considerable variation in 

composition and in range of monoterpenes (Smith 1977, Smith 1982a), and 

these 29 hybrids show this to be so. (Of course, the extent of the variation 

depended on the individual trees used in the breeding.) These 29 trees had a 

considerable range in several components plus having small amounts of 

heptane, nonane, and undecane in some trees; these latter three components 

were from P. montezumae and were typical of the species. Any time P. montezumae 

was involved in a cross (see #31 above, P. jeffreyi x P. montezumae), the progeny 

always had from 2 to 5 percent nonane; possibly this is evidence that a minor 

genetic structure might be active for the xylem monoterpenes in pines. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#79. P. ponderosa x P. jeffreyi.coulteri

Source n hep non α–p und cam ß–p car sab myr lim ß–ph ter 

------------------------------------percent: normalized 

S 1 69.0 2.0 13.0 2.0 * 2.0 1.0 1.0 3.0 * * -

S 1 66.0 2.0 15.0 * 1.0 1.0 1.0 1.0 4.0 1.0 1.0 -

S 1 80.0 1.0 8.0 1.0 1.0 1.0 1.0 * 3.0 1.0 1.0 -

The above format is explained in the introduction to this chapter. 

All three were full siblings, and there was a small range in their 

composition, probably reflecting the range of natural variation. The average 

composition is much like that of #41 above, P. jeffreyi.coulteri x wind. 

#80. P. ponderosa var. scopulorum x wind 

Source n α–p cam ß–p car myr lim ß–ph ter 

--------------------------------- percent: normalized ----------------------

TR 4 5.8 0.1 18.2 55.1 7.0 10. 0.3 2.7 

8 TR 1 7.6 * 28.9 30.6 9.0 22.2 * 1.6 

TR 1 5.8 0.5 0.4 86.0 2.9 * 1.0 3.3 

The above format is explained in the introduction to this chapter. 

The four trees should be like those of #82, below, but the average 

composition was quite different, suggesting that var. scopulorum is quite 

variable. The four trees above are about what would be expected: high 

3-carene, low α–pinene, and moderate amounts of ß–pinene, myrcene, 

and limonene. 

#81. P. ponderosa var. scopulorum x P. ponderosa var. scopulorum 

Source n α–p cam ß–p car myr lim ß–ph ter 

------------------------ percent: normalized -------------------------------

TR 4 16.6 0.1 25.2 44.9 3.5 5.9 0.6 3.2 

TR 1 5.8 0.3 20.3 63.3 4.1 0.4 1.6 4.2 

TR 1 46.8 * 16.6 29.0 2.1 2.9 0.7 1.9 

The above format is explained in the introduction to this chapter. 

The distribution of P. ponderosa var. scopulorum was generally considered to 

be northern and central Rocky Mountains. Yet it was not at all clear where the 

line was drawn between this variety and the other two varieties of P. ponderosa. 

The P. ponderosa trees from the Rocky Mountains in Chapter 3 can be described 

as high 3-carene and low α–pinene. Thus, the average of the four trees listed 

above, with much higher α–pinene than would be expected, suggested that the 

parent trees were from the southern Rocky Mountains where var. scopulorum 

merges with the high α–pinene containing var. arizonica. Of the two 

individually listed trees, the first was about as expected of an intervarietal 

cross, low in α–pinene. The second individually listed tree was more like one 

expected from a cross of var. scopulorum with var. arizonica, high in α–pinene. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#82. P. ponderosa var. scopulorum x P. ponderosa

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter

---------------------------------percent: normalized 

TR 6 18.1 0.1 21.3 39.0 8.0 10.0 0.6 0.1 2.7 

TR 1 5.1 - 23.8 50.5 4.8 12.4 - - 3.3 

TR 1 25.3 0.3 16.4 40.5 11.4 2.0 1.1 * 3.0 

S 1 32.0 1.0 7.0 35.0 11.0 12.0 1.0 * 2.0 

The above format is explained in the introduction to this chapter. 

The average and individual listings were nearly identical to the reciprocal 

cross given in item #75 above. 

#83. P. ponderosa var. scopulorum x P. ponderosa var. arizonica 

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter 

----------------------------- percent: normalized 

TR 2 15.5 0.1 47.2 28.2 4.4 1.6 1.2 0.1 1.8 

The above format is explained in the introduction to this chapter. 

The average of the two trees was quite low for α–pinene, if one assumes that 

var. arizonica was high α–pinene. Beta-pinene was usually high in both trees, 

considering the low ß–pinene in both varieties; but a combination of two (0-1) 

alleles, i.e., one from each parent, could have produced the large amount of ß– 

pinene by a (1-1) set of alleles in the progeny; however, this would have to be 

coupled with a combination of two sets of (0-1) or (0-0) alleles for α–pinene, 

resulting in a(0-0) or (0-1) set for α–pinene in some of the progeny. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#84. P. ponderosa var. scopulorum x P. engelmannii

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter 

---------------------------------percent: normalized 

TR 8 28.4 * 6.0 52.7 2.8 4.8 0.7 0.4 4.0 

TR 1 13.3 * 1.3 61.7 4.1 15.5 - - 3.6 

TR 1 52.7 * 7.9 33.1 2.0 1.0 0.5 0.1 2.7 

TR 1 4.1 * 18.3 67.2 4.7 * 1.6 0.4 3.6 

S 1 54.0 2.0 13.0 26.0 2.0 1.0 * * 2.0 

S 1 51.0 1.0 15.0 28.0 1.0 1.0 1.0 * 2.0 

S

These trees were full siblings. 

The above format is explained in the introduction to this chapter. 

The average composition of the eight trees was not what one would 

expect. The α–pinene was far below the intermediate level of about 45 percent, 

probably because var. scopulorum brings more alleles to the hybrid than does 

P. engelmannii. The latter probably had a (1-1) set of alleles for α–pinene and 

therefore at least one allele in the progeny. That is, it could be possible that the 

first listed tree (13.3 percent (α–pinene) had two alleles for 3-carene and one 

allele each for α–pinene and limonene. The range of composition was quite 

large, as shown by the three individually listed trees. An earlier report (Smith 

1967a) showed two full siblings to have almost identical compositions. 

#85. P. ponderosa var. scopulorum x P. montezumae** 

Source n non α–p und cam ß–p car myr lim ß–ph γ–ter ter 

----------------------------------- percent: normalized 

TR 4 3.5 14.7 5.5 0.5 9.0 53.6 5.1 2.9 1.1 0.1 4.3 

TR 1 3.5 9.0 5.7 0.9 13.1 51.9 7.0 4.6 1.5 0.1 2.9 

TR 1 4.4 11.6 5.4 * 3.0 64.8 3.9 1.5 1.4 0.1 4.0 

The above format is explained in the introduction to this chapter. 

The α–pinene was much lower than the expected, 45 percent, for a hybrid 

involving P. montezumae; nevertheless, the male parent was P. montezumae 

because of the nonane in the four progeny. The 2 to 4 percent nonane had been 

a marker in other crosses with P. montezumae. This further suggested that there 

must be P. montezumae with low α–pinene and high 3-carene also present; other 

components in the resin composition resembled var. scopulorum. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#86. P. ponderosa var. arizonica 

Source n α–p cam ß–p car sab myr lim ß–ph ter 

--------------------------------percent: normalized 

TR 14 90.3 0.2 4.9 0.1 1.5 0.7 0.5 0.2 1.0 

TR 1 95.8 0.3 0.7 - 1.2 0.7 0.3 * 1.0 

TR 1 70.1 0.5 1.8 - 14.1 1.4 0.3 0.2 11.2 

TR 1 40.3 - 55.7 - - 1.0 1.0 2.0 1.2 

M - 34.0 - 14.0 3.0 - 4.0 - - -

The above format is explained in the introduction to this chapter. 

Though this variety of P. ponderosa had been established for a longtime, the 

limits of distribution are not at all clear. Mirov (1961) gave it species status, as 

P. arizonica, whereas Critchfield and Little (1966) gave it variety status, and that 

will be used here. However, studies by Peloquin (1984) and Smith (1977) and 

data in Chapter 3 of this volume pose some questions about its distribution. In 

Chapter 3, the area considered var. arizonica has been divided into three regions 

and one transition zone on the basis of types of monoterpene composition. The 

average of the 14 trees reported here showed var. arizonica to have a (1-1) set of 

additive alleles for α–pinene. Yet, two of the trees listed had either a large 

amount of ß–pinene or sabinene and terpinolene; these were some of the 

variations reported in Chapter 3 of this volume. Mirov (1961) reported about 60 

percent α–pinene, 20 percent ß–pinene, and 5 percent 3-carene for var. arizonica. 

The ratio of sabinene to terpinolene was nearly 1:1. I also found small amounts 

of sabinene in some trees in the region assigned to var. arizonica (Smith 1977). 

#87. P. ponderosa var. arizonica x wind 

Source n α–p cam ß–p car myr lim ß–ph ter 

----------------------------- percent: normalized 

TR 9 91.2 0.3 7.3 * 0.7 0.8 0.3 -

TR 1 95.2 0.3 0.9 - 0.7 2.6 0.3 -

TR 1 54.9 0.2 42.6 - 0.8 0.8 0.9 -

TR 1 88.5 0.2 9.3 - 0.6 1.5 * -

The above format is explained in the introduction to this chapter. 

These nine trees differed from the previous hybrid (#86) only in being 

designated as wind pollinated. The average for the nine trees was very much 

like that of #86 above, and the individually listed trees were also similar. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#88. P. ponderosa var. arizonica x P. ponderosa 

Source n α–p cam ß–p car myr lim ß–ph ter 

------------------------------ percent: normalized --------------------------

TR 8 20.0 * 25.1 44.9 5.7 1.5 0.6 2.2 

TR 1 21.5 * 20.6 47.1 7.1 0.5 0.7 2.4 

TR 1 15.4 * 23.0 48.4 4.8 5.2 0.3 3.0 

S 1 28.0 * 22.0 39.0 3.0 4.0 1.0 2.0 

The above format is explained in the introduction to this chapter. 

The compositions of these eight intraspecific hybrids—all full siblings— 

were about as expected from such a cross, and the average was generally 

similar to the reciprocal, #75 above. The α–pinene in these trees above was far 

less than intermediate, probably because P. ponderosa brings more than one 

competing gene to the combination. Similar results were reported earlier by 

Smith (1967a). 

#89. P. ponderosa var. arizonica x P. engelmannii 

Source n α–p ß–p car myr lim ß–ph 

TR 1 

----------------------------- percent: normalized 

96.9 1.4 - 1.7 * *

The above format is explained in the introduction to this chapter. 

Both var. arizonica and P. engelmannii can be classed as having a (1-1) set of 

additive alleles for α–pinene. Thus, this hybrid was exactly what one would 

expect. 

#90. P. ponderosa.engelmannii x P. engelmannii 

Source n non α–p cam ß–p car myr lim ß–ph ter 

TR 5 ------------------------------percent: normalized 

0.7 73.7 0.3 14.4 5.1 2.4 3.0 0.4 0.2 

TR 1 - 69.5 0.3 29.2 - 0.2 0.2 0.7 0.1 

TR 1 - 55.2 0.2 0.6 25.4 6.1 11.7 - 0.8 

TR 1 3.5 90.6 * 2.0 - 3.8 - - -

The above format is explained in the introduction to this chapter. 

The average composition of the five trees showed much higher α–pinene 

than the female parent type (see #76 above), again suggesting a (1-1) set of 

additive alleles in the P. englemannii male parent. The range of composition was 

to be expected considering the range of composition in hybrid #76 above. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#91. P. ponderosa.engelmanni x P. jeffreyii.ponderosa 

Source n hep non α–p cam ß–p car myr lim ß–ph ter 

---------------------------------percent: normalized 

TR 3 8.7 0.1 33.1 0.1 12.9 21.7 3.6 17.8 0.3 1.7 

TR 1 26.1 0.2 37.1 2.4 3.3 5.5 25.3 - -

TR 1 * - - 32.4 1.0 7.8 1.0 2.6 

The above format is explained in the introduction to this chapter. 

The high α–pinene characteristic of P. engelmannii had been lost in this 

backcross. The α–pinene of P. engelmannii could have been reduced to a (0-1) 

set in the first cross with P. ponderosa, and further reduced to a (0-0) set in the 

backcross with the second P. ponderosa. Or, the addition of alleles from P. jeffreyi 

and P. ponderosa could have lowered the amount of α–pinene. 

#92. P. ponderosa.engelmannii x P. ponderosa 

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter 

----------------------------- percent: normalized 

1 4.7 * 35.8 40.4 * 12.3 1.9 * 4.4 

The above format is explained in the introduction to this chapter. 

The high α–pinene characteristic of P. engelmannii has been lost in this 

backcross. The α–pinene of P. engelmannii could have been reduced to a (0-1) 

set of alleles in the first cross with P. ponderosa, and further reduced to a (0-0) set 

in the backcross with the second P. ponderosa. 

#93. P. ponderosa.engelmannii x P. montezumae 

Source n non α–p und cam ß–p car myr lim ß–ph γ–ter ter 

----------------------------------percent: normalized 

TR 6 3.5 43.7 0.9 0.1 13.6 27.3 3.5 4.9 0.7 * 1.3 

TR 1 2.5 20.1 * - 14.5 50.1 7.0 0.1 0.9 * 2.6 

TR 1 1.6 76.5 * 0.1 15.0 - * 5.7 1.0 -

TR 1 3.2 89.0 2.2 0.3 2.1 - 0.8 1.5 0.6 -

The above format is explained in the introduction to this chapter. 

As noted earlier, whenever P. montezumae was involved in a cross there will 

be 2 to 5 percent nonane in the progeny. These six trees all had 2 to 5 percent 

nonane. The range in the remainder of the components was great, as one would 

expect with crosses of P. montezumae and P. ponderosa. That there was a 

consistent presence of nonane in low amounts in P. montezumae and its crosses 

leads one to suspect a minor genetic structure in pines for monoterpenes or 

related hydrocarbons. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#94. Pinus rigida x wind 

Source n α–p cam ß–p car myr lim ß–ph 

------------------------------------------------------percent: normalized 

TR 9 39.6 0.2 33.0 * 1.0 1.0 24.3 

TR 1 26.2 0.2 0.4 - 1.2 1.1 70.9 

TR 1 21.1 0.3 41.8 - 1.7 1.0 34.2 

TR 1 92.9 - 0.8 - 0.1 * 6.0 

TR 1 35.9 0.3 42.8 - 0.2 1.8 18.7 

TR 1 53.5 0.1 43.4 - 0.5 1.9 0.7 

M 65.0 - 20.0 - - - 10.0 

The above format is explained in the introduction to this chapter. 

The five individually listed trees showed great range in P. rigida in α– 

pinene, ß–pinene, and ß–phellandrene, and even with only nine trees as a basis 

one can discern three levels for α–pinene and phellandrene: low, medium, 

high. Mirov (1961) listed high α–pinene and ß–pinene and a small amount of 

limonene but did not list ß–phellandrene. Additional data on P. rigida are given 

in Chapter 8. 

#95. P. rigida x P. taeda** 

Source n α–p cam ß–p car myr lim ß–ph 

----------------------------------- percent: normalized 

S 1 75.0 2.0 9.0 - 4.0 2.0 9.0 

The above format is explained in the introduction to this chapter. 

The measurements for this one hybrid was about what might be expected 

with α–pinene and ß–pinene from both parents and ß–phellandrene from P. 

rigida. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#96. P. rigida.taeda x P. taeda 

Source n α–p cam ß–p car myr lim ß–ph 

----------------------------------- percent: normalized --------------------------------------

TR 10 58.7 1.0 27.2 0.1 2.6 1.5 8.7 

TR 1 77.8 - 6.1 0.8 1.4 0.7 13.3 

TR 1 49.0 * 33.2 - 2.4 0.3 15.1 

TR 1 60.1 8.9 12.3 - 0.6 0.4 17.7 

TR 1 61.3 * 36.6 * 1.2 0.5 0.4 

The above format is explained in the introduction to this chapter. 

The effect of both parents was reflected in the average composition and in 

most of the individually listed trees. The one tree with only a trace of ß– 

phellandrene suggested that this component had a (0-1) set of additive alleles 

in P. rigida. The one tree with 9 percent camphene was well above the level in 

either parent. Camphene was probably nongenetic in origin, or might be 

attributed to isomerization; or the production of camphene could also be a 

response to some external stimulus. 

#97. P. rigida.taeda x P. clausa 

Source n α–p cam ß–P car myr lim ß–ph 

--------------------------------- percent: normalized --------------------------------------

TR 82.5 0.6 2.0 - 1.0 4.5 9.1 

The above format is explained in the introduction to this chapter. 

The low ß–pinene in this three-way hybrid was not what might be expected. 

Mirov (1961) reported P. clausa as high ß–pinene, and both P. rigida and P. 

taeda (previously discussed) had small to moderate amounts of ß–pinene. 

However, if all three had a (0-1) set of additive alleles for ß–pinene, it would be 

possible to have very low ß–pinene in the progeny. 

#98. P. rigida.taeda x P. echinata.taeda 

Source n α–p cam ß–P myr lim ß–ph 

----------------------------percent: normalized 

TR 3 71.2 0.2 25.1 2.1 0.7 0.5 

TR 1 63.5 0.2 32.6 2.9 - 0.6 

TR 1 82.5 0.1 14.3 2.7 - 0.1 

The above format is explained in the introduction to this chapter. 

In the four-way cross, the three progeny seemed more like P. taeda or P. 

echinata than P. rigida. The P. rigida parent could have been without ß– 

phellandrene, as noted under #94 above, or ß–phellandrene could have been 

lost in the cross with P. taeda. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#99. Pinus strobiformis

Source n hep α–p und cam ß–p car sab my lim ß–ph

----------------------------------percent: normalized 

TR 6 - 71.3 - 0.6 22.3 - 2.8 1.3 0.3 0.3 

TR 1 - 68.6 - 1.1 17.5 - 6.5 0.8 0.8 1.3 

TR 1 - 92.6 - - 1.0 - 1.5 4.9 -

TR 1 - 62.2 - 1.0 36.1 - - - 0.5 0.1 

M 1 5 75.0 3 - - 5 - - - -

S 1 - 69.0 - 2.0 10.0 - 17.0 - - -

The above format is explained in the introduction to this chapter. 

Mirov (1961) reported this species as P. reflexa, and it was often used as a 

synonym for P. strobiformis. Mirov postulated that on the basis of monoterpenes, 

P. strobiformis (i.e., reflexa) was not closely related to P. flexilis, but Smith (1967a) 

showed considerable similarity, particularly in the presence of moderate 

amounts of sabinene. Likewise, Critchfield and Little (1966) reported that P. 

strobiformis and P. flexilis introgress where they were sympatric in northern 

New Mexico and southern Colorado. The lack of terpinolene in the last listed 

tree is puzzling because there was a substantial amount of sabinene. Could this 

species be different from other pines and not have the sabinene-terpinolene 

linkage? 

#100. P strobus x P monticola 

Source n α–p cam ß–p myr lim ß–ph 

----------------------------percent: normalized 

TR 7 58.3 0.5 39.5 0.7 0.4 0.5 

TR 1 64.3 2.3 31.7 0.8 0.5 0.5 

TR 1 47.8 1.2 47.8 1.3 0.7 1.4 

S 1 48.0 1.0 48.0 1.0 1.0 1.0 

The above format is explained in the introduction to this chapter. 

The average composition of the seven trees, the composition of the 

individually listed trees, and that of the tree reported earlier (Smith 1967a) all 

show only small variations, yet, one would expect much more. There were 

several differences between this cross and its reciprocal, #52 above, i.e., there 

was no undecane, sabinene, or 3-carene in this set of crosses. However, the 

great variation in the monoterpenes of P. monticola (See #12 of Chapter 3) could 

explain such differences; it depended on the particular P. monticola used. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#101. P. strobus x P. griffithii** 

Source n α–p cam ß–p car myr lim ß–ph 

------------------------------- percent: normalized 

TR 7 71.2 0.8 26.6 - 0.5 0.5 0.4 

TR 1 71.7 0.3 26.9 - 0.5 0.3 0.2 

TR 1 80.0 1.8 16.6 * 0.4 0.5 0.4 

S 1 57.0 5.0 36.0 - 1.0 * * 

The above format is explained in the introduction to this chapter. 

Mirov (1961) reported that P. griffithii (as P. excelsa) was nearly 90 percent 

α–pinene. Thus, again, intermediacy was not reached because of the 

introduction of other competing genes into the biosynthetic system—in this 

case, ß–pinene. 

#102. Pinus taeda x wind 

Source n α–p cam ß–P myr lim ß–ph 

TR 7 ----------------------------- percent: normalized 

79.0 0.1 18.0 2.3 0.4 0.3 

TR 1 75.0 - 21.9 2.6 0.4 0.1 

TR 1 94.3 * 2.8 2.5 0.3 0.1 

M 71.0 22.0 * * 

1 374 60.0 1.0 30.0 3.0 - -

1

Coyne and Keith (1972) 

The above format is explained in the introduction to this chapter. 

The average composition for the nine trees was much like that given by 

Mirov (1961) and not appreciably different from that given by Coyne and Keith 

(1972), who analyzed 374 trees. The range, shown by the two individually listed 

trees, was well within the results given by Coyne and Keith (1972). 

#103. P. taeda x P. taeda 

Source n α–p cam ß–p myr lim ß–-ph 

----------------------------percent: normalized 

TR 1 70.7 0.5 26.8 1.0 - 1.0 

The above format is explained in the introduction to this chapter. 

This one tree was quite similar to those listed for P. taeda x wind above, 

#102. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#104. P. taeda x P. echinata 

Source n α–p cam ß–p myr lim ß–ph 

-------------------------- percent: normalized 

TR 1 61.8 0.3 33.5 3.7 * 0.8 

The above format is explained in the introduction to this chapter. 

The composition of this one tree was almost identical to the average 

composition of 38 reciprocal crosses in item #15 above. In more than 40 P. taeda 

x P. echinata hybrids listed in this report, not one had more than a small amount 

of limonene; yet Coyne and Keith (1972) reported moderate amounts of 

limonene, up to about 20 percent, in a few trees of both species. Apparently, the 

selection of the parent trees used in the breeding did not include trees with this 

characteristic. From the amounts of limonene listed by Coyne and Keith (1972) 

one might expect a (0-1) set of additive alleles in a few trees of each species. 

#105. P. taeda x P. rigida 

Source n α–p cam ß–p α–ph myr lim ß–ph 

--------------------------------- percent: normalized 

TR 3 49.6 0.4 35.5 0.1 1.1 0.4 12.9 

TR 1 44.5 0.4 38.4 0.1 1.4 * 15.1 

TR 1 45.5 0.3 45.2 0.1 1.0 0.3 7.6 

The above format is explained in the introduction to this chapter. 

This hybrid was about as expected with a large amount of α–pinene and ß– 

pinene, and with a moderate amount of ß–phellandrene. The differences 

between this set of progeny and those of the reciprocal, #95 above, could be 

explained by the additive allele hypothesis. 

#106. P. taeda.elliottii var. elliottii x P. elliottii var. elliottii 

Source n α–p cam ß–p myr lim ß–ph 

------------------------------ percent: normalized -----------------------------

TR 1 52.2 * 19.7 17.5 * 10.3 

The above format is explained in the introduction to this chapter. 

This one backcross retained all the general characteristics of both species: 

α–pinene and ß–pinene of P. taeda, and myrcene and ß–phellandrene of P. 

elliottii var. elliottii. 

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Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent Species Smith 

#107. P. taeda x P. echinata.taeda 

Source n α–p cam ß–p myr lim ß–ph 

---------------------------percent: normalized 

TR 3 71.9 0.3 23.5 3.4 - 0.3 

The above format is explained in the introduction to this chapter. 

The composition of the three trees was about the same as P. taeda x P. 

echinata in #104 above. 

#108. Pinus virginiana x wind 

Source n α–p cam ß–P myr lim ß–ph 

-------------------------------percent: normalized 

TR 6 53.4 0.3 44.0 0.9 0.2 1.3 

TR 1 33.5 0.4 62.2 0.9 1.1 1.9 

TR 1 21.2 0.2 76.2 0.9 * 1.5 

M - 98.0 - - - - -

The above format is explained in the introduction to this chapter. 

The average composition was quite unlike that given by Mirov (1961). In 

fact, none of the six trees was at all like that of Mirov (1961) who reported P. 

virginiana as near-pure α–pinene. The difference between the two reports could 

have been caused by the small sample size. 

#109. Pinus virginiana x P. clausa** 

Source n α–p cam ß–p myr lim ß–ph 

------------------------------percent: normalized 

TR 5 26.4 0.4 69.8 0.9 0.8 1.8 

TR 1 33.5 0.4 62.2 0.9 1.1 1.9 

TR 1 20.6 0.1 74.0 1.1 1.7 2.5 

The above format is explained in the introduction to this chapter. 

Mirov (1961) listed P. clausa with about the highest level of camphene, 

about 10 percent, in any pine. Yet, nothing more than a trace of camphene could 

be found in any of the five hybrids. Mirov (1961) also listed P. clausa with 10 

percent α–pinene and 75 percent ß–pinene. The small number of sampled trees 

of the hybrids could explain this; or camphene may not be of genetic origin but 

may be a product of isomerization, and this isomerization had not yet taken 

place in these hybrids at IFG. 

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Smith Monoterpene Composition of 88 Hybrids and 24 Parent Species Chapter 4 

#110. P. washoensis x wind

Source n α–p cam ß–p car myr lim ß–ph ter 

----------------------------percent: normalized 

TR 5 7.7 0.8 29.2 41.4 12.7 5.3 0.5 2.2 

TR 1 8.5 0.2 18.3 55.6 13.7 0.7 0.1 3.0 

TR 1 6.2 0.1 31.2 38.1 11.7 10.6 2.2 

S 1 17.0 * 27.0 37.0 12.0 4.0 2.0 2.0 

S 1 9.0 - 31.0 44.0 7.0 5.0 1.0 3.0 

The above format is explained in the introduction to this chapter. 

The average and range of the five trees was about as expected, with high 3-

carene, moderate ß–pinene, and smaller amounts of α–pinene, myrcene, and 

limonene. The ratio of 3-carene to terpinolene ranged from 15:1 to 20:1, which 

was expected. These trees were also similar to those described in previous 

reports (Smith 1967a, Smith 1971). See Chapter 3, #19, for additional information 

on P. washoensis. The ratio of 3-carene to terpinolene varied from 10:1 to 20:1. 

#111. P. washoensis x P. ponderosa** 

Source n α–p cam ß–p car myr lim ß–ph ter 

------------------------- percent: normalized 

TR 15 8.4 0.2 27.5 41.4 13.4 6.1 0.2 1.8 

TR 1 3.9 0.1 14.2 56.2 12.8 9.4 - 3.3 

TR 1 6.8 0.2 37.7 33.0 19.4 0.8 - 2.1 

TR 1 9.5 0.2 22.2 35.3 13.2 17.7 * 1.8 

The above format is explained in the introduction to this chapter. 

The average composition of these 15 trees was well within the expected 

composition. They really are no different than P. ponderosa and were very 

similar to the reciprocal, #77 above. 

#112. P. washoensis x P. ponderosa var. scopulorum** 

Source n α–p cam ß–p car myr lim ß–ph γ–ter ter 

-------------------------------- percent: normalized 

TR 2 5.9 0.1 33.9 44.6 9.7 2.0 1.7 0.4 2.8 

The above format is explained in the introduction to this chapter. 

These two were quite similar to some of those listed in the previous item 

#111. 

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