United States 

Department 

of Agriculture 

Forest Service 

Pacific Southwest 

Research Station 

General Technical Report PSWGTR- 177 

Xylem Monoterpenes of Pines: 

Distribution, Variation, Genetics, 

Function 

Richard H. Smith 
Publisher 

Albany, California 

Mailing address: 

PO Box 245, Berkeley CA 

94701-0245 

(510) 559-6300 

http://www.psw.fs.fed.us 

July 2000 

Pacific Southwest Research Station 

Forest Service 

U.S. Department of Agriculture 

Abstract 

Smith, Richard H. 2000. Xylem monoterpenes of pines: distribution, variation, genetics, 

function. Gen. Tech. Rep. PSW-GTR-177. Albany, CA: Pacific Southwest Research 

Station, Forest Service, U.S. Department of Agriculture; 454 p. 

Retrieval Terms: Pinus species, pine grafts, bark beetles, western pine beetles, gas liquid 

chromatography, California. 

The monoterpenes of about 16,000 xylem resin samples of pine (Pinus) species 

and hybrids—largely from the western United States—were analyzed in this 

long-term study of the resistance of pines to attack by bark beetles (Coleoptera: 

Scolytidae), with special emphasis on resistance to the western pine beetle 

(Dendroctonus brevicomis). The samples were analyzed by gas liquid 

chromatography, and the results reported are expressed as normalized 

monoterpene composition. Optical isomers were not separated. The study 

covered (a) 19 pine species in California, (b) 86 pine hybrids and 26 parent 

species at the Pacific Southwest Research Station's Insitute of Forest Genetics, (c) 

21 half sibling populations of Pinus ponderosa Dougl. ex Laws., (d) 56 full sibling 

populations of P. ponderosa, (e) interspecific and intraspecific pine grafts, (f) 

effects of procedural parameters, and (g) bioassay of resistance to Dendroctonus 

brevicomis. The results suggested that (a) these monoterpenes and associated 

hydrocarbons were primarily controlled by genes in pine xylem—hepane, 

undecane, α–pinene, ß–pinene, 3–carene, sabinene, myrcene, limonene, ß– 

phellandrene—and evidence strongly suggested a pair of additive alleles for 

each monoterpene that competes with each other for a fixed amount of a fivecarbon precursor; (b) all of these might also be produced by isomerization and 

possibly may be byproducts of biosynthesis of other monoterpenes; (c) the 

quantity of all these can be modified by several environmental factors often 

associated with forms of stress, and possibly by other minor genetic factors; an 

(d) these monoterpenes were not controlled by genes in pines but are probably 

the results of isomerization and byproducts of biosynthesis: α–thujene, nonane, 

camphene, γ–terpenene, ocimene, α–phellandrene, and terpinolene. 

The Author: 

Richard H. Smith, a research emtomologist, was Project Leader—Forest Insect 

Research, headquartered in Berkeley, California, until his retirement in 1989. 

Much of his 33-year career at the Pacific Southwest Research Station was 

spent on studying the resistance of pines to bark beetles, including action of 

pine resins in resistance, and on the biology, ecology, and control of forest 

insect pests. Before joining the Pacific Southwest Station staff in 1955, he 

served as a research entomologist for 8 years at three locations in the eastern 

and southern United States. 

Cover Image: Chapter 6, Figure 6-2. 
Xylem Monoterpenes of Pines: 

Distribution, Variation, Genetics, Function 

Richard H. Smith 

Contents 

Acknowledgments ..................................................................................................v

In Brief...................................................................................................................vi

Chapter 1 General Introduction ...........................................................................1 

Chapter 2 General Procedures .............................................................................7

Collection and Preparation of Resin Sample .......................................7

Chromatographic Analysis .................................................................8

Data Analysis .....................................................................................9

Chapter 3 Distribution and Variation of the Xylem Monoterpenes of the 

19 Pine Species of California ............................................................11

Pinus albicaulis Engelm. (whitebark pine) ......................................13

Pinus aristata Engelm. (bristlecone pine) .......................................20

Pinus attenuata Lemm. (knobcone pine) .......................................23 

Pinus balfouriana Grev. and Balf. (foxtail pine) .............................28

Pinus contorta Dougl. ex Laud (lodgepole pine) ............................28 

Pinus coulteri D. Don (Coulter pine) .............................................38

Pinus edulis Engelm. (Colorado pinyon pine) ................................48

Pinus flexilis James (limber pine) ...................................................50

Pinus jeffreyi Grev. and Balf. (Jeffrey pine) ....................................50

Pinus lambertiana Dougl. (sugar pine) ..........................................53 

Pinus monophylla Torr. & Frem. (single leaf pinyon) ....................71

Pinus monticola Dougl. (western white pine) .................................87 

Pinus muricata D. Don (Bishop pine) ............................................99 

Pinus ponderosa Dougl. ex Laws. (ponderosa pine) ......................101 

Pinus quadrifolia Parl. (Parry pine) ...............................................124 

Pinus radiata D. Don (Monterey pine) ..........................................126 

Pinus sabiniana Dougl. (Digger pine) ..........................................129 

Pinus torreyana Parry (Torrey pine) .............................................129 

Pinus washoensis Mason and Stockwell (Washoe pine) ...............133 

Chapter 4 Monoterpene Composition of 88 Hybrids and 24 Parent

Species at the Institute of Forest Genetics .......................................141 

Pacific Southwest 

Research Station 

USDA Forest Service

General Technical 

Report 

PSW-GTR- 177 

July 2000 

i 
Table of Contents Xylem monoterpenes of pines: distribution, variation, genetics, function Smith 

Some General Statements About Monoterpenes ......................... 142

Explanation of Format ................................................................ 143 

Pinus attenuata ........................................................................... 144

Pinus brutia ................................................................................ 146 

Pinus contorta ............................................................................. 147 

Pinus coulteri .............................................................................. 150 

Pinus echinata ............................................................................ 150 

Pinus elliottii ............................................................................... 153 

Pinus engelmannii ....................................................................... 153 

Pinus flexilis ................................................................................ 156 

Pinus greggii .............................................................................. 156 

Pinus griffithii ............................................................................. 157 

Pinus halepensis ......................................................................... 158 

Pinus jeffreyi ............................................................................... 159 

Pinus longifolia ........................................................................... 167 

Pinus monticola .......................................................................... 167 

Pinus muricata ............................................................................ 170 

Pinus nigra .................................................................................. 171 

Pinus patula ................................................................................. 175 

Pinus pinaster ............................................................................. 176 

Pinus ponderosa ......................................................................... 177

Pinus rigida ................................................................................ 189 

Pinus strobiformis ....................................................................... 191 

Pinus strobus ............................................................................... 191 

Pinus taeda ................................................................................. 192 

Pinus virginiana .......................................................................... 194 

Pinus washoensis ........................................................................ 195 

Chapter 5 Population Studies of the Monoterpene Composition of 4 -to

12-Year-Old Half Siblings of P. ponderosa ................................ 197 

Selection of Parent Trees ............................................................ 199 

Nursery and Plantation Practices ................................................. 199 

Sampling for Resin ..................................................................... 201 

Tehachapi Transition Zone: Ranger Peak .................................... 202 

Sierra Pacific Region: Adin-Placerville ....................................... 209 

Escalante North Transition Zone: Wheeler Peak ......................... 213 

Comparison of Progeny of Parents with Similar Composition . 216

Comparison of Progeny of Parents with Dissimilar Composition .238

Multiple-Tree Comparisons ................................................ 248 

Types of Composition ......................................................... 274 

Discussion: Half-Siblings P. ponderosa .............................. 274 

Chapter 6 Monoterpene Composition of Populations of 4- to 11-YearOld Full Siblings of P. ponderosa ............................................... 287 

Crosses of P. ponderosa AS-3139 with 10 Pollen Sources ............ 293 

Crosses of P. ponderosa AS-A78 with Five Pollen Sources .......... 319 

Crosses of P. ponderosa AS-A95 with Six Pollen Sources ............ 332 

Crosses of P. ponderosa AS-5789 with Five Pollen Sources .......... 345 

Crosses of P. ponderosa AS-A295 with Three Pollen Sources....... 360 

Crosses of P. ponderosa AS-3187 with 10 Pollen Sources ............ 363 

Crosses of P. ponderosa IFG-4B63 with 12 Pollen Sources .......... 387 

Discussion: Full Siblings of P. ponderosa ...................................... 409 

ii USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Xylem monoterpenes of pines: distribution, variation, genetics, function Table of Contents 

Chapter 7 Grafted Pines ..........................................................................413

Interspecific Grafts ..................................................................414 

Intraspecific Grafts of P. ponderosa ........................................416 

Chapter 8 Measuring the Effects of Sampling and Operational 

Parameters: Regression, Trends Lines, Tabulation ..................425 

Chapter 9 The Function of Xylem Monoterpenes of Young P. ponderosa

during Western Pine Beetle Attack (Coleoptera: Scolytidae): 

A Bioassay...............................................................................435 

Materials and Methods ............................................................437 

Conclusions .............................................................................443 

Chapter 10 References ..............................................................................449 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 iii 
Smith Xylem monoterpenes of pines: distribution, variation, genetics, function Acknowledgement 

Acknowledgments 

The research, data analyses, and report preparation covered many years, and 

many people assisted me in this work. Therefore, knowing that I regrettably 

will miss citing some, I thank the following individuals who contributed 

significantly to the work: 

For their concepts and early studies of host relationship of pines to bark 

beetles and for their support of research on resin and host resistance: Charles B. 

Eaton, John M. Miller, and Nicholas T. Mirow, Pacific Southwest Research Station, 

Berkeley, Calif.; and James A. Beal, USDA Forest Service, Washington, D.C. 

For their helpful and timely guidance in data processing or for their helpful 

manuscript review, or both: Clarence J. DeMars, Jr., George T. Ferrell, Lula 

E. Greene, and Nancy G. Rappaport, Pacific Southwest Research Station. 

For the extensive use of their publications on the distribution of pines and 

pine resins: William B. Critchfield and Nicholas T. Mirov, Pacific Southwest 

Research Station; Elbert L. Little, USDA Forest Service, Washington, D.C.; 

James R. Griffin and Eugene Zavarin, University of California, Berkeley. 

For their valuable assistance in tree breeding and culturing: Carroll W. 

Busch, Edwin J. Carpender, Johnny P. Cramer, James L. Jenkinson, and Roger 

A. Stutts, Pacific Southwest Research Station. 

For his helpful and incisive editorial review of the manuscript: B. Shimon 

Schwarzschild, Pacific Southwest Research Station. 

For developing and executing the procedures for enhancing the numerous 

frequency distribution graphs: Hannah M. Knapp, my granddaughter 

For assistance in typing several chapters of the manuscript: Abigail K. 

Knapp, my other granddaughter. 

And finally and foremost, I dedicate this report to the memory of my wife 

Mary Louise Smith, without whose continuing and loving support I could not 

have completed this work: For her encouragement in the face of many 

obstacles, for her seemingly limitless understanding and devotion during 

the long periods of field research, for her services as a volunteer field 

assistant on several resin-collecting trips—usually under the guise of a 

vacation, and for the occasional use of her home as a temporary laboratory 

and a depository for the large volume of paper that resulted from a long 

manuscript-processing period. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 v 
In Brief Xylem monoterpenes of pines: distribution, variation, genetics, function Smith 

In Brief 

Smith, Richard H. 2000. Xylem monoterpenes of pines: distribution, variation, genetics, 

function. Gen. Tech. Rep. PSW-GTR-177. Albany, CA: Pacific Southwest Research 

Station, Forest Service, U.S. Department of Agriculture; 454 p. 

Retrieval Terms: Pinus species, pine grafts, bark beetles, western pine beetles, gas 

liquid chromatography, California. 

The monoterpenes are an important group of chemicals occurring in many 

plant species. They are particularly common and abundant in conifers— 

especially the pines (Pinus species). They are important because they have 

been associated with plant defense against insect attack and disease 

infection. Quite the opposite, they might also act in attracting insects to 

plants directly or indirectly. They are used for plant classification. And 

commercially, they are used as solvents and can be building blocks in the 

synthesis of organic chemicals. 

This report brings together both published and unpublished information 

about the distribution, variation, genetics, and function of the xylem 

monoterpenes of pines. The reported studies are largely derived from a longterm investigation of the host relationship of bark beetles (Dendroctonus) to the 

pines, with special emphasis on the resistance of ponderosa pine (Pinus ponderosa 

Dougl. ex Laws.) to the attack of western pine beetles (D. brevicomis) and the 

function of xylem resin in this relationship. The focus is on this relationship 

rather than on the study of monoterpenes as such. 

The monoterpenes of about 16,000 xylem resin samples of pine species and 

hybrids—largely from the western United States—were analyzed in this study of 

the resistance of pines to attack by bark beetles (Coleoptera: Scolytidae). The 

samples were analyzed by gas liquid chromatography, and the results reported 

are expressed as normalized monoterpene composition. Optical isomers were 

not separated. Results, by major study areas, were as follows: 

Variation and distribution of the xylem monoterpenes in the 19 pines of California: 

• The 19 species, which are found naturally in California, were sampled 

with a wide range of local and regional intensity. 

• Ten species had considerable local or regional variation or both in 

composition and can be characterized by the incidence of types of 

composition: ponderosa pine (P. ponderosa), lodgepole pine (P. contorta), 

singleleaf pinyon pine (P. monophylla), bristlecone pine (P. aristata), 

bishop pine (P. muricata), Coulter pine (P. coulteri), washoe pine (P. 

washoensis), whitebark pine (P. albicaulis), sugar pine (P. lambertiana), 

western white pine (P. monticola). The last three, all soft pines, are 

extremely variable locally and regionally, and may have as many as 40 

composition types in a stand of 100 trees. 

vi USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Xylem monoterpenes of pines: distribution, variation, genetics, function In Brief 

• Three species have little or no variation and can be characterized fairly 

adequately by average composition: Jeffrey pine (P. jeffreyi), Digger 

pine (P. sabiniana), knobcone pine (P. attenuata). 

• Six species have some variation, but the data currently available are 

insufficient to permit characterization by the type of composition: 

foxtail pine (P. balfouriana), Torrey pine (P. torreyana). Parry pine (P. 

quadrifolia), pinyon pine (P. edulis), limber pine (P. flexilis), and 

Monterey pine (P. radiata). 

• In every adequately sampled species, the frequency distribution of one 

or more of their individual monoterpenes was multimodal, often 

trimodal, giving some support to the hypothesis that the genetic 

structure for each monoterpene is due primarily to the additive effect of 

two alleles at a single locus. 

Xylem monoterpenes composition of 86 inter- and intra-specific pine hybrids 

and 26 parent species at the Station's Institute of Forest Genetics (Chapter 4): 

• The 86 inter-and intra-specific pine hybrids and 26 parent species 

growing in the arboretum at the Pacific Southwest Research Station's 

Institute of Forest Genetics, near Placerville, California, are catalogued 

in Chapter 4. 

• Most of the parent species are from North America, but a few are from 

Central America and Eurasia. 

• Much of the data are from a study of P. ponderosa, P. jeffreyi, P. coulteri, 

and loblolly pine (P. taeda). 

• The number of trees sampled for a given parent or hybrid was usually 

small, and only generalizations can be offered; and the actual parents of 

most hybrids were almost always unavailable for terpene analysis. In 

many cases, the pollen was from 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 two parent species. The lack of close intermediacy, 

though, 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. 

Populations of 4- to 12-year-old half sibling families of P. ponderosa (Chapter 5): 

• Chapter 5 reports population studies of 4- to 12-year-old half siblings of 

P. ponderosa, mostly nursery grown. These half-siblings were from 

parent trees in three widely separated geographical areas. Full siblings 

were derived from many of these same parent trees. 

• Studies included about 1500, four to 12-year-old half siblings of 27 trees 

that were selected primarily on the basis of monoterpene composition. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 vii 
In Brief Xylem monoterpenes of pines: distribution, variation, genetics, function Smith 

Three of the ecotypic (monoterpene races) regions of P. ponderosa were 

represented: Tehachapi, Sierra Pacific, and Escalante, and results were 

based on 25 to 200 siblings per parent. 

• Composition usually varied greatly in two or more major components. 

• Average composition of a set of progeny tended to be broadly

intermediate between the parent tree and the average of the local stand.

Trees with similar composition produced progeny that were quite 

similar in composition. 

• Limonene and myrcene content, however, were lower than expected

when intermediacy prevailed, and α–pinene and ß–pinene were higher. 

A juvenile effect is postulated which is more or less evident in all young

growth. The effect of this juvenile factor is much the same as that shown 

by plants under stress. All young trees or young parts of older trees, 

therefore, may be under some level of stress—the stress of rapid growth. 

• Nearly one-third of the half siblings of a high limonene parent could be 

classed as high limonene or potentially so. 

• Some high limonene trees were found among the progeny of a parent

which could be classes only as near-high limonene. 

• A rare tree was found with ultra high limonene, i.e., with about 70 pct.,

though such trees have not been found in mature, natural stands. 

• There were some differences between the three regions in the 

comparative ratios between parent and progeny of a given 

monoterpene, suggesting that the locality of a parent tree has an effect 

of the juvenile response or that there are minor genetic effects which are 

distinctive to a region. 

• Two forms of stress—over-application of a phytocide and prolonged 

growth in a container—caused a sharp change in quantitative 

composition, usually evidenced by lower limonene and myrcene and 

higher α–pinene and ß–pinene. 

Results, in general, indicate that the quickest and cheapest way to obtain trees 

with a diverse array of composition is the use of wind pollinated seed from 

localities with much variation in individual tree composition. 

Population studies of 4- to 12- year-old full sibling families of P. ponderosa (Ch.6): 

• About 3,000 samples of 4- to 12-year-old full siblings of 56 sets of 

progeny from 7 females and 14 male trees were examined. 

• Forty-two sets of progeny were analyzed for modal distribution of 

individual monoterpenes. In all cases, the actual number of modes 

derived from the analysis equalled or exceeded the number of modes 

expected from the assignment of additive alleles to the two parents; this

supports the additive allele hypothesis for five monoterpenes in P. 

ponderosa: α–pinene, ß–pinene, 3-carene, myrcene and limonene; 

myrcene, though, appears to be a rare allele. 

• High limonene content trees always breed true, but the juvenile effect 

was clearly evident in the progeny. 

viii USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith Xylem monoterpenes of pines: distribution, variation, genetics, function In Brief 

• Other combinations of parents also produced high limonene progeny. 

• Crosses of high limonene trees produced progeny which could be 

classed as ultra-high limonene—about 80 pct—a type of composition 

not yet found in natural stands. Many other types of composition 

were found among the progeny which have not yet been found in 

natural stands. 

• The composition of a single set of progeny was quite variable, 

suggesting the effects of several non-genetic factors on the basic 

genetic structure. 

• Differences between the progeny of a female with two males which 

were near and far away from the female were noticeable. These 

differences were evidenced in much the same way as stress; and it is 

postulated that there is a level of stress in the progeny of parents which

are far apart, or possibly "off-site". 

• The effects of stress were clearly evident in full siblings, and were often 

greatest in trees with high limonene concentration. 

• Breeding on grafts produced the same array of progeny as breeding on 

the parent tree. 

• Over an 8-year period there were no sharp shifts in the composition of a

set of progeny in a given location; this indicates slow changes over 

many years: α–pinene and ß–pinene decreasing, myrcene and 

limonene increasing, and 3-carene increasing or decreasing,

depending on the composition. There probably will be an increase in 

ß–phellandrene with age. These observations are based on sampling

different sets of trees from the same population, and not on 

resampling the same set of trees. 

There was no decrease in total seed or sound seed per cone in crossing parents

about 500 miles apart; and progeny of such crosses are not growing nearly as 

well as indigenous progeny. 

Inter- and intra-specific grafts (Chapter 7): 

• Chapter 7 is a report on 40-year-old interspecific grafts of pine species 

and of 12-year-old intraspecific grafts of P. ponderosa. 

• Forty years after grafting, the composition of the scion of inter-specific

grafts—ponderosa /Jeffrey, Jeffrey/ ponderosa, Digger/ponderosa— 

was about the same as the parent species, but the composition of the

root stock was being affected by the scion and the effect was 

proportional to the distance from the graft union. 

• Measurements were made of 6- to 17-year-old intra-specific grafts of 

P. ponderosa. 

• The qualitative and quantitative composition of the scion was radically

different from the parent tree for about 10 years after grafting. The

greatest differences were in grafts in which the composition of the root 

stock and the scion were most widely divergent. Three possible causes 

are postulated: (1) the severe stress of grafting, (2) a strong effect of the 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 ix 
In Brief Xylem monoterpenes of pines: distribution, variation, genetics, function Smith 

root stock, (3) an expression of a minor genetic structure through the 0-

0 set of alleles. 

• Between 10 and 17 years after grafting, but primarily between 15 and 

17, the composition of the scion suddenly and rapidly became much 

like that of the parent tree. 

• After this sudden change, the scion began to affect the composition of 

the root stock much as in older inter-specific grafts noted above. 

Effect of sampling and procedural parameters (Chapter 8): 

• Trees over 40 years old had little or no difference in composition 

attributable to radial, or circumferential position of the sample. There 

was small and consistent variation attributable to vertical position of the 

sample in 40 to 60 years old P. ponderosa: α–pinene and ß–pinene

decreased slightly from top of the tree to the bottom, and myrcene and 

limonene increased slightly. 

• Little or no change in composition took place during a 9-year interval 

between resampling the same large number of P. ponderosa. 

• For P. ponderosa under 15 years old, there maybe significant quantitative 

shifts in the topmost two to four internodes. 

• No effects on analysis could be attributed to variations in type of 

sample preparation or time of storage of whole resin samples. However, 

there were very large qualitative and quantitative differences between 

results in this report, and those results on which the monoterpene 

sample was derived from steam distillation of mill-ground sapwood. 

• There was a marked difference between xylem and cortex resin 

monoterpene composition of P. ponderosa. 

Bioassay of resistance to western pine beetle (Chapter 9): 

• Eight to 12-year-old P. ponderosa, derived from the half and full siblings

studies, were used; the procedure was forced attack on irreversibly 

stressed trees. 

• Success of attack of D. brevicomis was inversely proportional to 

both the concentration of limonene and to the quantitative flow 

of xylem resin. 

• In general, trees of the size tested—about 2 to 3 inches in diameter— 

were relatively resistant; but within this relatively resistant state, good 

comparative determinations were made. 

Stress: 

Six growth conditions, noted under previous headings, were deduced as 

stressful in P. ponderosa under 17 years of age: juvenile period of growth, rapid

growth, great distance between parents, over-application of phytocides, 

prolonged root containment, and grafting. All six were evidenced by an increase 

in ß–pinene and α–pinene, and by a decrease in myrcene and limonene. 

x USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Chapter 1 

General Introduction 

Summary: Resins are complex mixtures of organic chemicals. They are found 

in many kinds of plants, commonly in conifers, and particularly in the pines. 

Resins or their components can protect the plant from insect attack and disease 

infection. On the other hand, they can also attract insects. Monoterpenes, 

constituents of pine resin that have an empirical formula of C10H16 , are quite 

volatile and have been associated with both plant resistance and attraction. 

Monoterpenes have been used in plant classification, as organic solvents, and 

as base molecules in the commercial synthesis of organic compounds. Though 

strongly controlled by genes, monoterpenes are quantitatively quite variable in 

pines, probably due in a large part to the competition of sets of additive alleles 

for a fixed amount of C-5 precursor. Smaller quantitative variation appears to 

come from isomerization, from biosynthetic by-products, from several 

conditions of stress, and from age. This paper reports results of a study on the 

host relationship of pines to bark beetles. 

This paper describes the xylem monoterpenes of pines: their distribution, 

variation, function, and genetics. Monoterpenes are quite volatile and generally 

give pines their characteristic fragrance. Though all monoterpenes have the 

same empirical formula, they vary in structure, primarily in the position of 

rings and double bonds. The overall evidence suggests (a) that the following 

monoterpenes and associated hydrocarbons found in pine xylem resin are 

primarily controlled by genes: heptane, undecane, α-pinene, ß-pinene, 3-carene, 

sabinene, myrcene, limonene, ß-phellandrene; (b) that the genetic mechanism 

is a pair of additive alleles at a single locus for each of these components; (c) 

that the above components might also be produced by isomerization and 

possibly may be by-products of the biosynthesis of other monoterpenes; (d) 

that the quantity of these monoterpenes can be modified by a number of 

environmental factors, often associated with forms of stress and possibly by 

other minor genetic factors; and (e) that the following are not controlled by 

genes but are probably the result of isomerization and by-products of 

biosynthesis: α-thujene, nonane, camphene, gamma-terpinene, ocimene, αphellandrene, and terpinolene. These conclusions are based on gas-liquid 

chromatographic (GLC) analysis and other recorded measurements. 

Xylem resin of pines is often and simply defined as a supersaturation of 

rosin (resin acids) in turpentine (terpenes). The word "resin" can be quite 

limited to products of conifers (Mirov 1961) or to a wide variety of plants 

(Langenheim 1990). The terpenes are volatile liquids and are largely 

monoterpenes with an empirical formula of C10H16; they generally comprise 

about 25 percent of the total weight of resin. The monoterpenes are defined as a 

class of terpenes containing two isoprene molecules. The remainder of the 

liquid fraction is chiefly sesquiterpenes (C15H24); the amount of the latter in 

whole resin ranges from about 0 to 20 percent. Thus, the aggregate of all 

terpenes in whole resin ranges from about 25 to 45 percent. The monoterpenes 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 1 
Chapter 1 General Intr

oduction Smith 

are much more volatile than the sesquiterpenes. There are several resin systems 

in pines distinct from each other, including needle, bud, cone, cortex, root, as 

well as xylem. In xylem, resin is formed in the epithelial cells surrounding the 

resin ducts. 

The general assumption has been that resin is an end product of metabolism 

and does not enter any other subsequent biosynthetic processes. 

The natural function of resin in pine xylem has long been debated and 

discussed. A general hypothesis is that resin protects the tree from insect attack 

and disease infection. Although this hypothesis has usually been at a 

generalized level without specific documentation, there seems to be some 

evidence to support the protection hypothesis. 

The close association of xylem resin of pines with the success or failure of 

bark beetle attack has been studied for a long time, starting with observations 

by A. D. Hopkins (1909), followed by early experimental work by Miller (1950), 

Callaham (1955), Vité and Wood (1961), and by experimental breeding and

bioassay by Smith (1982b). Richmond (1985) showed that pine oil—a liquid 

aggregate of pine resin extracts with limonene as the primary constituent— 

could, when applied as a spray to the trunk, protect P. contorta from attack by

the Dendroctonus ponderosae. One interesting and dramatic exception to the protective function is the very different role that resin plays in the operation of 

bark beetle pheromones. In these cases, one or more of the monoterpene

constituents of P. ponderosa actually synergize the action of bark beetle pheromones to make them more potent attractants. Thus, the presence of the particular monoterpene in xylem resin helps to concentrate bark beetle attacks on a specific tree or to localized areas and helps to make the attacks more 

successful. There also is some evidence that monoterpenes may be used by bark 

beetles to make pheromones. Chapter 9 will give experimental evidence that 

resin can function in the resistance of pines to bark beetle. 

Constituents of resin, particularly the monoterpenes, have been used in 

plant taxonomy, in the differentiation of species and varieties and in the

verification of hybrids. 

In addition to its natural functions, xylem resin has been used by humans 

for a variety of purposes for thousands of years. In much of the period of

wooden ships, resin was used as the caulking material for joints; thus, the 

origin of the term "naval stores," i.e., materials used by the navy. Resin and its 

derivatives have served as a fuel, solvent, and source of fragrance. As a solvent 

it is quite commonly used in paints. Recently, there has been renewed interest 

in the use of turpentine as a general organic solvent. Hayes (1988) contends that 

turpentine might be substituted for many halogenated solvents that are so 

widely used in industry but which are often much more environmentally

hazardous than a natural product such as turpentine. Monoterpenes can be 

used as base molecules in the synthesis of organic compounds, such as 

paclitaxex (Wender 1997 a, b). The current status of the commercial use of resin 

was reviewed by Zinkel (1981).

Early work on the identity of the xylem monoterpene in pines was 

summarized by Mirov (1961). That work simply reported the aggregate identity

within a species; it was usually necessary to combine samples from several 

trees to obtain the amount of resin needed for the analyses used at that time. 

Thus, Mirov's work primarily reported that there was a wide range in 

monoterpene composition among some of the pine species throughout the 

world. Mirov (1961) gave some evidence for regional variation in a couple of 

species, but the report lacks evidence of local variation among trees of the same

species.

The rapid analysis of small samples of resin became possible with the 

development of gas chromatography. This permitted the analyses of large 

2 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith General Introduction Chapter 1 

numbers of individual trees and the basis for determining local and regional 

varieties of the xylem monoterpenes of pines, and for determining the genetic 

basis for these characteristics. The results of some of these studies encouraged a 

theory on the co-evolution of pines and bark beetles (Mitton and Sturgeon 

1982). I reviewed the book (Smith 1985) and cited several aspects of the 

relationship of western pine beetle Dendroctonus brevicomis to P. ponderosa that 

do not fit the requirements of the co-evolution hypothesis. 

The following are 10 generalizations about the biosynthesis and genetics of 

xylem monoterpenes in pines: 

1. A large body of evidence shows that the total amount of the aggregate of 

the monoterpenes in whole xylem resin is quite constant for the pines at 

about 25 percent (Bannister and others 1962, Mirov 1961, Zavarin and 

others 1969). This evidence is particularly strong for P. ponderosa (Smith 

1977) with an average of about 25 percent monoterpenes in nearly 3,000 

trees measured; and this 25 percent figure was true for trees throughout 

the range of the species. Therefore, the normalized system and the 

absolute quantitative system are strongly related. This assumption is 

strengthened by data given in Chapter 8 on sampling parameters which 

showed, in general, that there was little variation in normalized 

composition with differences in temporal and spatial sampling, and with 

variations in the preparation and analysis of samples from mature trees. 

2. The best evidence is that there is a C-5 precursor for all monoterpenes— 

and probably for the sesqui- and di-terpenes as well (Sandermann 1962). 

Two molecules of C-5 precursor unite to form a single molecule of C-10 

monoterpene. The addition of another C-5 unit forms a C-15 

sesquiterpene. And the total amount of the monoterpenes appears to be 

quite constant. 

3. A fixed amount of this C-5 precursor is probably produced—or there is a 

biosynthetic feedback regulatory mechanism which keeps the amount 

fairly constant—which the monoterpene alleles, through their respective 

enzymes, draw upon. This results in a de facto competition between the 

monoterpene alleles for the C-5 precursor. Thus the amount of a given 

monoterpene depends not only on its own genetic makeup but also on 

the genetic makeup of the other monoterpene alleles. For example, a 

tree with alleles for only α-pinene will have a monoterpene composition 

of nearly 100 percent α-pinene. But a tree with the same alleles for αpinene and also with alleles for other monoterpenes will have a 

monoterpene composition with much less than 100 percent α-pinene. 

4. The structure noted in (3) makes for theoretical quantitative intermediacy 

in the composition of progeny, but this intermediacy becomes less sharp 

in a system in which there are two or more different sets of alleles 

between the two parents. Thus, in a species like P. ponderosa where there 

is clear evidence of five major monoterpenes, the discrimination of alleles 

and loci becomes less clear and more difficult. 

5. Five additional conditions can also reduce the sharpness of allelic 

discrimination: 

(a) the ever-present variation in any biological system; 

(b) the long periods during which xylem resin remains in place and 

subject to environmental and biological forces, including isomerization; 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 3 
Chapter 1 General Introduction Smith 

(c) the variation, though small, in the sampling and analytical 

procedures; 

(d) the possible presence of a minor genetic structure; 

(e) the action of several forms of stress. 

6. Empirical evidence, from an extensive study of the local and regional

variation of the xylem monoterpenes of P. ponderosa, shows a tendency

for each of the five major monoterpenes of P. ponderosa and other pines 

to have at times and under some circumstances a trimodal frequency

distribution (Smith 1977). This trimodality suggests two additive 

alleles at a single locus for each gene. For a working hypothesis and 

for the discussion of the results, the values of 0 and 1 are assigned 

to these two alleles so that each gene can have one of three allelic 

structures (0-0, 0-1, or 1-1). 

7. To test the genetic hypothesis and get the best resolution, it would be 

advisable to work with many different types of parent trees and large 

numbers of progeny. Because of logistics and the limited nature and 

purpose of the study, the best parent trees and number of progeny could 

not be selected in the studies reported herein. That is, the basic goal of 

many of the studies was the production of trees with desirable types of 

composition and not the study of gene structure. 

8. The monoterpenes in xylem resin can be generally classed as major or 

minor depending on the amount present. Major components are α-pinene, 

ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, and 

the related hydrocarbons heptane and possibly undecane. In general, 

these occur at greater than 15 percent in at least some trees. Minor 

components occur at less than 15 percent. 

9. A discussion of the minor monoterpene components, which are nearly

always less than 15 percent, might be helpful at this time, since they will 

be discussed only briefly within the text. The more common minor 

components are α-thujene, camphene, α-phellandrene, gammaterpinene, ocimene, terpinolene. 

10. There are at least four explanations for the presence of small amounts of 

these minor monoterpenes: (a) isomerization, (b) biosynthetic byproducts, (c) slight activity by the 0-0 set of alleles, and (d) a minor

genetic effect, though there is no firm research evidence for such a 

structure. And the explanation may not be clearly resolved easily because

the preparation and analytical procedures are not that well-tuned for 

such small amounts of materials. However, large numbers of samples 

may offset this inadequacy. 

(a) Isomerization: This is a most likely explanation. All monoterpenes

have the same empirical formula; they differ only in molecular 

configuration. The change from one isomer to another can take place

easily and with little energy. An example of this is ß-phellandrene. In

analytical samples from trees with a large amount of ß-phellandrene,

the amount of ß-phellandrene sometimes quickly decreases, even under 

refrigeration, with irregular shifts in the amounts of the 

remaining monoterpenes; and the sample usually changes to a more

viscous state. The change to a more viscous state suggests 

4 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Smith General Introduction Chapter 1 

polymerization. In trees like P. rigida and P. elliottii, the amount of ßphellandrene can vary more than usual from one location to the other 

in the tree, suggesting isomerization. The effects of age may also be an 

indication of isomerization. Camphene, α-phellandrene, and gammaterpinene are often lacking or in very small amounts in young trees, 

but they begin to be present in trace and small amounts as the tree 

ages. Myrcene and limonene also increase with tree age. 

(b) Biosynthetic by-products: There are at least two clear linkages in the 

monoterpenes of pines, 3-carene to terpinolene, and sabinene to 

terpinolene. The ratio of 3-carene to terpinolene is usually about 15:1 

while sabinene to terpinolene ranges from 3:1 to about 1:1. In these 

linkages the ratios are large enough to measure; it might be possible 

for other linkages to exist, but the ratios are too small or variable. 

There do not seem to be alleles for terpinolene because it is never 

found except in relationship to 3-carene or sabinene. Therefore 

terpinolene might be called a biosynthetic by-product. 

(c) Activity by the 0-0 set of alleles: Trees like P. jeffreyi and P. sabiniana, 

which appear to have a (1-1) set of alleles for heptane, usually have 

trace to small amounts of several monoterpenes. Though these small 

amounts could be derived from isomerization of heptane by a 

pathway which is not yet known, it might be that (0-0) pairs of alleles 

for these monoterpenes are slightly active. In some backcrosses in 

hybrids, a monoterpene occurs in small amounts where one would 

expect either a moderate amount from a (0-1) set of alleles or none at 

all from a (0-0) set. 

(d) A minor genetic effect: There were some small differences between 

the sets of progeny of one female with two different males with the 

same monoterpene composition and with the same assignment of 

alleles. This difference could be attributed to a minor structure which 

has not yet been resolved. Such a structure could produce small to 

trace amounts of monoterpenes. 

Additional introductory material, specific to a topic, will be given at the 

beginning of the appropriate chapter. 

Review of literature was terminated in 1990, when the first draft of the 

full manuscript was completed, except for the articles by Wender (1997). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 5 
Chapter 2 

General Procedures 

Summary: All analyses were of fresh resin extracted by tapping large trees and 

by mini-tapping or severing small trees. Nearly all samples were prepared for 

analysis by dilution in chromatographic pentane. Analysis of a sample was by 

gas-liquid chromatography, with a thermal conductivity detector, using a 

column of ß, ß ́ oxydipropionitrile. Optical isomers were not separated. 

Composition of individual trees was determined by normalization of peak 

areas for the monoterpene portion of whole resin. Composition of stands was 

best expressed by the characteristics of the frequency distribution of the amount 

of the individual monoterpenes. Stands or species that were quite variable in 

composition were subjected to a coding procedure that classified all trees into a 

limited number of monoterpene types of composition. The numbers of trees in 

each coded type were subjected to statistical analyses in order to compare 

stands or regions. 

Much of this chapter consists of the general procedures for sample 

collection, preparation and analysis, and of data analysis carried out by the 

author. Additional procedures that are specific to a chapter will be given, when 

necessary, in a section at the beginning of that chapter. The procedures for cited 

work will not be given. Most were generally so similar to those given here that 

results were considered comparable. However, Mirov (1961), prior to the 

availability of GLC (gas liquid chromatography), often obtained his sample by 

open-faced collection similar to commercial naval stores practice. He usually 

aggregated the resin from several trees for analysis, and separated terpenes 

from resin acids by vacuum distillation. He separated the volatiles into 

individual components by fractional distillation. For limited sampling for his 

later work, Mirov did use closed-face collection by employing a 1-inch punch 

tap fitted with a 30-cc collection vial. 

Collection and P`reparation of Resin Sample 

Some early sampling was done with the 1-inch punch tap noted above for 

Mirov. However, two procedures were used for nearly all sampling of living 

trees, a 0.56-inch diameter macro-tap and a 0.25-inch diameter micro-tap. 

For a macro-tap, a hole was made through the bark and for about 0.25 inch 

into the xylem using a brace and 0.56-inch bit. Nearly all sampling was done 

within the basal 3 feet of the tree except for studies on the effect of height of 

sample. Often it was helpful to shave down the area of bark so that the entry 

hole could be more easily made. This shaved area of the bark also facilitated the 

location of tapped trees when the collection vials were retrieved. The hole had 

a slightly upward slant to facilitate the flow of resin into a vial. The hole was 

cleared of debris and the collection vial, a 5-cc shell, was inserted directly into 

the entry hole so that the lip of the vial was past the phloem and cambium and 

just into the xylem. Collection vials remained in place for 8 hours to 2 days 

depending on resin flow and the schedule of field activities. The short period 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 7 
Chapter 2 General Procedures Smi

th 

was more than adequate, in hot weather and at low elevation, when sampling 

good resin-producing trees like P. ponderosa, P. lambertiana, P. monophylla. The 

long period was needed in cold weather, at high elevation, and for poor resinproducing trees like P. albicaulis, P. contorta. 

Collection vials were tightly corked and taken to the laboratory for sample 

preparation. Collected samples were usually put on ice if there was a long period—of several days—between collection and preparation. 

For a micro-tap, a 0.25-inch diameter hole was drilled through the bark and 

phloem for about 0.25 inch into the xylem using a hand brace. The hole was 

slanted 30°-45° downward so that the bottom of the hole acted as a collecting 

reservoir for the xylem resin as it exuded from the xylem. The hole was cleared 

of debris. Resin was collected from the catchment hole by using a thin glass rod. 

A large drop of resin was picked up with the glass rod and placed in a 1-cc 

screw-cap sample vial and taken to the laboratory for sample preparation. 

Usually 20 to 30 vials were collected at one time and taken to the laboratory for 

immediate processing. This procedure was used only for trees that were within 

30 minutes of a laboratory, though it could be used at any time with the use of 

a portable laboratory. Procedures for sampling severed trees will be given in 

Chapter 5. 

Samples were prepared for analysis by adding an approximately equal 

volume of chromatographically pure pentane to the freshly collected resin 

sample. Nearly all prepared samples were held in 1-cc screw-cap vials. Pentane 

is the best solvent for the chromatographic column because it elutes from the 

column before any monoterpenes. For the micro-tap samples, the pentane was 

simply added to the vial in which the glass rod sample had been placed. These 

prepared samples were stored at 0° C except during analysis. A portable field 

laboratory was used for some of the sample preparation of the 19 pine species 

of California. 

In some limited and early work (1963-65), the sample of gross resin was 

distilled in a small short-path still, such as a Hickman still, and the liquid 

fraction was used for analysis without the use of a solvent. No difference in 

analysis was found between pentane-prepared and still-prepared samples. 

Chromatographic Analysis 

All samples were analyzed for monoterpenes by gas-liquid chromatography 

with a thermal conductivity detector. The column was stainless steel, 1/8 inch 

by 6'-12' with a solid phase of 80/100 mesh chromosorb W/AW and a liquid 

phase of 5 percent ß, ß ́ oxydipropionitrile (Klouwen and ter Heide 1962). Operating 

temperatures were 63° C to 68° C on the injector, and 150° C to 160 ° C on the 

column and on the detector. The carrier was helium at 20 to 40 ml per minute. 

The monoterpenes were not separated into optical isomers. 

In the early years (1963-1980), the sample analysis was recorded by a 

continuously balancing strip recorder with a disc integrator to measure peak 

areas of each monoterpene and the total peak area for a sample or a tree; peak 

areas were then normalized. In the later years (1980-1989), a programmed 

electronic integrator was used with immediate calculation and display of 

normalized peak areas. Both devices gave identical or nearidentical results 

with the same sample. Size of the injected sample varied from 0.2 to 1.0 ul, and 

time of sample analysis varied from 8 to 15 minutes depending on operating 

parameters. 

Identification of peaks was periodically checked by internal standards or 

by preparative recovery and reanalysis of individual peaks, but most peaks 

were identified by reference to previous samples or to mixtures of known 

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

th General Procedures Chapter 2 

monoterpenes. Two alternate columns, apiezon and LAC, were sometimes 

used to check identity. 

Some observations about the ß, ß ́ column are worth noting. Over the 

course of the work, numerous columns with the same specification were used, 

because the ß, ß ́ column usually performs adequately for only 3 to 6 months. 

Yet, all columns did not perform the same initially or subsequently. Some were unable to totally or adequately separate heptane from the pentane solvent. 

There also were two sets of monoterpenes which were not always clearly 

separated: 3-carene/sabinene, and limonene/myrcene/ß-phellandrene. 

Deterioration of a column showed up as a gradual decline in the degree of 

separation of those sets of components. Deterioration was usually irreversible; 

yet occasionally, a column would improve in response to a period of rest. 

Glass-wool plugs were placed at the far end of the injector nearest the column 

and between the injector and the column. These acted as traps for the solid 

portions of the resin sample to keep them from slowly migrating onto the 

column, thus lowering the separation capabilities of the column. Changing the 

glass-wool plugs—daily in the injector and weekly between the column and the 

injector—was found to lengthen the useful life of a column, and to slightly 

improve the separation of components. 

Data Analysis Individual trees: The a

mounts of components in the sample from each tree were

always normalized. That is, each monoterpene was expressed as a percentage

of the total monoterpenes in the sample. Normalized expression will be used

throughout this report, both for the author's work and for cited work.

The use of normalization has been questioned by some researchers who 

prefer to express the xylem monoterpenes as an absolute quantity. However, I 

and others have considerable data to support normalization, as noted earlier in 

the Introduction. Additionally, I have made hundreds of measurements to 

determine any change in normalized composition due to time of sampling, 

position of sample in the mature tree, and differences in procedure. The results 

showed the normalized composition to be very constant; the results are reported 

in Chapter 8. Therefore, I believe normalization is valid and as appropriate as 

any other procedure for expressing monoterpene composition. Likewise, 

because the monoterpene portion of xylem resin is nearly always at about 25 

percent, absolute concentration can be approximated by reducing the 

normalized amounts by 75 percent. 

Sets of trees, basic statistics: Whenever there were two or more trees in a set, 

the basic statistics of mean, maximum, minimum, and standard deviation 

(S.D.) were calculated for each component. This was a standard procedure for 

most data, not so much for interpretation, but to maintain a standard base for 

all sets of data. These figures have limited interpretive value, particularly if 

there is considerable range in components; they could be misleading because of 

multimodal distributions. 

Sets of trees, frequency distribution: Whenever there were sufficient numbers 

of trees in a set—usually greater than 30—the frequency distribution of each 

component was plotted. From this display of the data, one can see whether the 

distribution is a single mode or multimodal, and how the individual 

measurements are distributed among the modes. These displays have very 

good interpretive value. These also provided a way to present concisely a large 

volume of data and to show the range and abundance of the percentages of 

monoterpene components in a stand or species. 

Sets of trees, composition types: Whenever there was a multimodal 

distribution for one or more monoterpenes within a plot, as shown by the 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 9 
Chapter 2 General Procedures Smith 

frequency distribution just discussed, the trees in the set were classified into 

types of composition. The limits of each mode were derived directly from the 

frequency distribution. In nearly all cases three modes were described, and 

these were given values of 0, 1, or 2 for the low, middle, and high mode. Then 

the composition of each tree was reduced to a coded composition by converting 

the actual composition to a single digit of 0, 1, or 2 according to the modal 

location of the actual value. This caused a reduction in the number of types of 

composition in the set of trees; these sets were quite suitable for statistical 

procedures. The number of trees in each coded type was determined, and the 

whole set of trees was normalized by composition types, i.e., the number of 

trees of each coded type was expressed as a percentage of all the trees in the set. 

A program (MacDonald and Green 1988) was sometimes used to refine and 

analyze the multimodal distribution. This program assists in determining the 

number of modes in each distribution and in defining their means and their 

proportions; it will be described more fully in the section on full siblings 

(Chapter 6). 

I believe that in examining local and regional variation of stands of a 

species, there is excellent analytical and interpretive value in the characteristic 

of frequency distribution of individual components. I further believe that the 

most meaningful, concise, and accurate way to characterize a stand of trees or a 

species, where there is considerable variation, is by the frequency of types of 

composition, because all components are viewed as a unit in a tree. Any 

procedure that uses individual components, such as means and standard 

deviation, or some form of principal component analysis may not be as effective 

or meaningful because of normalization and the interdependence of the 

components. Frequency of composition types can be used only if a species has 

variation in one or more components. It cannot be used for trees that have little 

variation, like P. jeffreyi, P. sabiniana, and P. attenuata. The coded expression of 

composition types may also coincide to some degree with the genetic 

constitution of a stand or species. The composition types are derived from the 

frequency distributions. 

10 USDA Forest Service Gen. Tech. Rep. PSW-GTR-177.2000 
Chapter 3 

Distribution and Variation of the Xylem 

Monoterpenes of the 19 Pine Species of 

California 

Summary: The 19 pine species that are found naturally in California were 

sampled with a great range of local and regional intensity, 12 by the author and 

7 by others. All trees were greater than 30 years old. Little or no variation in 

composition could be attributed to the time or place of sampling the tree. The 

major monoterpenes, usually greater than 15 percent in at least some trees, 

found among the 19 species are: α–pinene, ß–pinene, 3-carene, sabinene, 

myrcene, limonene, ß–phellandrene. The minor components, usually less than 

15 percent in nearly all trees, are: camphene, γ–terpinene, terpinolene, 

tricyclene, ocimene, ρ–cymene. Three related hydrocarbons—heptane, nonane, 

and undecane—can also occur as minor components in some species. Heptane 

is a major component in two species. Ten species have considerable local and/ 

or regional variation in composition. They can be characterized by the incidence 

of types of composition: P. ponderosa, P. contorta, P. monophylla, P. aristata, P. 

muricata, P. coulteri, P. washoensis, P. albicaulis, P. lambertiana, and P. monticola. 

Some of the soft pines are extremely variable locally and regionally and may 

have as many as 40 composition types in a stand of 100 trees. Numbers of 

composition types for a species ranged from 9 to 120. The P. ponderosa species 

was divided into seven regions and four transition zones on the basis of 

composition types. Three species, P. jeffreyi, P. sabiniana, P. attenuata, have little 

variation and can be characterized fairly adequately by average composition. 

The remaining six species have some variation, but the data currently available 

are insufficient to permit characterization of types of composition: P. balfouriana, 

P. torreyana, P. quadrifolia, P. edulis, P. flexilis, and P. radiata. In every adequately 

sampled variable species, the frequency distribution of one or more of the 

individual monoterpenes was multimodal, often trimodal, supporting the 

hypothesis that the genetic structure of each monoterpene is primarily two 

additive alleles at a single locus. Optical iomers were not separated. 

This chapter reports the distribution and variation of the xylem monoterpenes 

of the 19 pine species native to California. Eighteen species were sampled in 

California, and some of these were sampled beyond California for the more 

widely distributed species in the western United States. Data for P. edulis were 

taken from a cited article in which all samples were from trees outside California. 

Twenty-three pine species are found naturally in western United States 

(Critchfield and Little 1966), with 19 found in California (Griffin and Critchfield 

1972). Information on their general distribution, to the extent of the research 

coverage in this report, has been compiled in table 3-1. 

An alternate way of listing the 19 species is by taxonomic classification 

(table 3-2), but I will not follow this order. The four pine species in western 

United States not found in California are those whose principal distribution 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 11 
Chapter 3 19 Pine Species of California Smith 

Table 3-1—The 19 pine species of California, their generalized distribution in western United States(*), the degree 

of coverage in this report, and the principal scientists reporting on xylem monoterpenes for each species 

Species 

Pinus 

Generalized Coverage in Principal

distribution this report

1 research2 

Only Mostly

Calif. Calif. 

Western

U.S. Local Regional 

1. P. albicaulis *a 1 3 S 

2. P. aristata * 2 1 Z

3. P. attenuate * 1 2 S 

4. P. balfouriana * 1 1 Others

5. P. contorta *a 1 2 S 

6. P. coulteri *b 2 1 S 

7. P. edulis * 3 1 Z

8. P. flexilis *a 3 3 S 

9. P. jeffreyi *b 1 1 S 

10. P. lambertiana *b 1 1 S 

11. P. monophylla * 1 2 S/Z

12. P. monticola *a 1 3 S/Z

13. P. muricata * 1 2 Others

14. P. ponderosa *ab 1 1 S 

15. P. quadrifolia *b 2 1 Z

16. P. radiate 3 * 1 1 Others

17. P. sabiniana 1 2 S 

18. P. torreyana * 1 1 Z

19. P. washoensis *c 1 1 S 

1 1 =extensive, 2 = fair, 3 = sparse. 2 S = RH Smith; Z = Eugene Zavarin and associates; 

Others = other than S or Z. 3 Recent work gives varietal status to stands on the islands off northern Baja California. 

a: also in Canada; 

b: also in Mexico; 

c: also in Nevada. 

Table 3-2—The taxonomic ordering of the 19 pine species of California within the genus Pinus as derived 

from Critchfield and Little (1966) 

Subgenus Section Subsection Species 

Strobus Strobus Cembrae 

Strobus Strobi 

Parrya Cembroides 

Parrya Balfourianae 

Pinus Pinus Ponderosae 

Pinus Sabinianae 

Pinus Contortae 

Pinus Oocarpae 

P. albicaulis 

P. monticola 

P. lambertiana 

P. flexilis 

P. edulis 

P. quadrifolia 

P. monophylla 

P. balfouriana 

P. aristata 

P. ponderosa 

P. washoensis 

P. jeffreyi 

P. sabiniana 

P. coulteri 

P. torreyana 

P. contorta 

P. radiata 

P. attenuate 

P. muricata

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

th 19 Pine Species of California Chapter 3 

is in Mexico, with their northern limits extending into the other States 

bordering on Mexico. These four species are: P. leiophylla, P. discolor, P. 

engelmannii, and P. strobiformis. 

The 19 pines will be covered in this report in alphabetical order (table 3-1).

Briefly included will be some of the published work of the author and a large

volume of unpublished data that have been collected over a period of about 15 

years. Publications of others will be reviewed to the extent that some 

information will be given for each of the 19 species; however, review of 

published work will not be extensive. 

Both the local and regional coverage varied greatly among the 19 species

(table 3-1). Early in the study of variation in xylem resin monoterpenes, it

became apparent that a better description of species with considerable variation 

would be secured with a larger sampling of local populations that would 

define the population by the frequency of types of composition rather than by

average differences between individual components. Description by individual 

components seems to be the least adequate for species with variation in 

composition. For example, it is possible for two stands to be nearly alike for the

average of the various components, yet they can be quite different in the 

characteristics of the frequency distribution of individual components and in 

the frequency of types of composition. To work with types of compositions, it is 

generally necessary to have 50 to 100 trees in a sample. Frequency distributions 

for modes were not statistically analyzed for the 19 species because of unknown 

parentage. Modal analysis was carried out for full siblings of P. ponderosa (see

Chapter 6). Though the determination of composition types was based on criteria 

derived from the frequency distribution data, there may be a genetic basis for it 

as well. The information on the 19 species in this chapter is largely confined to 

xylem resin monoterpenes with little or no coverage of other attributes of the 

species. These other attributes have been studied for many of these species. 

The procedures used for much of the work reported in this chapter are

covered in Chapter 2. The GLC procedures for cited work varied, but they did not 

affect the results except in a few instances in which young seedlings were used

instead of mature trees. Such exceptions will be noted as they occur in the text. 

An additional sampling procedure successfully used by others for sampling the 

tree was to take an increment core of the sapwood and then extract the xylem 

monoterpenes with solvents. This procedure was particularly useful where trees 

were difficult to reach, and, therefore, it was not necessary to make the second 

trip to collect the resin sample if a tapping procedure had been used. To repeat,

optical isomers were not separated.

Only one sampling procedure seemed to produce results different from 

those described in this report. That procedure was to mill-grind fresh xylem 

and extract the volatiles by steam distillation (Anderson and others 1970).

There was no elaborate system for selecting trees to be sampled. The 

procedure was simply "the next tree." A "first tree" was chosen at the beginning

of the stand, and a tap was made. The "next tree" was the nearest tree forward 

when standing at the tap. The distance and direction of the next tree were noted 

so that they could be easily located for sample retrieval. In general, all trees were 

greater than 8 inches in diameter, without obvious defects, and greater than 30 

years old—most more than 40. Though the distance to the "nearest tree" was 

often more than 50 feet—a distance considered adequate for genetic research— 

there were many instances in which the distance was less than 50 feet. #1. Pinus albicaulis Engelm. (whitebark pine) P. albicaulis is the only North American pine in the subsection Cembrae, the nut pines, of the subgenus Strobus; the other four species in the subsection are 

Eurasian. P. albicaulis is found extensively in western United States and Canada USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 13 
Chapter 3 19 Pine Species of California Smith 

(fig. 3-1). It is largely limited to higher elevations, particularly in the southern 

portion of its range where it is often the pine found at the tree line. Mirov (1961)

reported the monoterpene fraction of P. albicaulis to be near-pure 3-carene; he

also reported unusually large amounts of sesquiterpenes, particularly

albicaulene. The discussion that follows is adapted from Smith (1990). Sampling

was limited to a very small portion of the species range. 

Three stands of P. albicaulis were sampled for xylem resin as follows: 

Number of National Mountain 

Trees Sampled Local Forest Range 

43 Mt. Rose, Nev. Toiyabe Sierra Nevada 

62 Mt. Shasta, Calif. Shasta-Trinity Cascades 

23 Paulina Mtns., Ore. Deschutes Cascades 

This sampled portion of the tree's range is characterized by small, widely 

separated stands at high elevation. All trees were probably greater than 40 

years old, though some were quite small. 

Results and Discussion 

The three P. albicaulis stands differed considerably in average composition of 

xylem monoterpenes and in the range of the components (table 3-3). However, 

no composition of any tree in the three stands resembled that which Mirov 

(1961) reported for the other four species of Cembrae—that is, high in α–pinene 

and ß–pinene. The two Cascade stands differed much more from the Sierra 

Nevada plot than they differed from each other, but there were noticeable 

differences between the two Cascade plots. Although in a normalized analysis 

a change in one component can cause a change in another, the total 

monoterpene content of whole resin was fairly constant. Thus, the normalized 

system is a close approximation of the absolute amounts, and the differences 

observed can be considered real. 

The major component in all trees at Mt. Rose was 3-carene, as Mirov (1961)

had reported (table 3-3). 3-Carene was also a major component at Mt. Shasta 

and Paulina Mountains. As with other pines there was a strong, positive 

association of 3-carene and terpinolene. However, the ratio of the two 

components was quite different in other pines; in P. albicaulis the ratio of 3-

carene to terpinolene was about 10:1. In most other pines, like P. ponderosa, it 

ranged from 20:1 to 15:1. 

The Mt. Rose trees also had small to moderate amounts of α–pinene, ß– 

pinene, myrcene, limonene, and ß-phellandrene. These same components were 

in larger amounts in the Mt. Shasta and Paulina Mountains trees; ß– 

phellandrene was generally a trace component in all trees. 

The individual component averages of the Mt. Rose stand differed 

markedly from those of the Cascade stands. The averages of several components 

were about the same in the two Cascade stands, but the ranges were usually

different. This could be caused by differences between the two stands in the 

size of the sample. That is, in a species so variable it may be necessary to have a 

large sample size—from my experience, 70 to 100 trees—to estimate the range 

of variation with confidence. The two Cascade stands differed markedly in the 

average and range of ß–pinene and 3-carene (table 3-3). The differences between 

the two stands in sabinene was caused by one tree at Paulina with 23 percent 

sabinene. As in several other pines there was a strong positive relationship

between sabinene and terpinolene, with nearly a 1:1 ratio—a ratio quite similar 

for the two components in P. monophylla, as will be shown later in this chapter. 

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

Figure 3-1—Location of three stands of 

P. albicaulis sampled for xylem resin 

monoterpenes: P = Paulina Mtns.; S = Mt. 

Shasta; R = Mt. Rose; distribution taken 

from Critchfield and Little (1966). 

Table 3-3—Average (X), maximum, and minimum xylem resin monoterpenes of Pinus albicaulis in 

three stands: Mt. Rose, Mt. Shasta, Paulina Mountains; n = number of trees in a stand; * = trace 

Mt. Rose Mt. Shasta Paulina Mts. 

Monoterpene n = 43 n = 62 n = 23 

χ Max-Min χ Max-Min χ Max-Min 

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

1

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

α-Pinene 1.9 4 - 1 2.7 8 - 2 2.9 5 - 0 

ß-Pinene 0.3 1 - * 4.6 39 - * 11.4 20 - 0 

3-Carene 83.2 94 - 70 54.0 82 - 40 45.1 68 - 8 

Sabinene2 0.0 0 - 0 0.0 0 - 0 1.0 23 - 0 

Myrcene 6.1 18 - * 28.1 44 - 1 27.8 69 - 16 

Limonene 1.0 5 - 0 3.6 11 - 0 3.4 14 - 0 

ß-Phellandrene 0.4 1 - 0 0.3 1 - 0 1.3 16 - 0 

γ-Terpinene * 0 - 0 * 0 - 0 * 0 - 0 

Terpinolene 6.9 14 - 0 6.0 11 - 4 6.8 20 - 2 

1

Normalized percent, * = trace. 2

Found in one tree at Paulina Mtns. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 15 
Chapter 3 19 Pine Species of California Smith 

Therefore, the same tree with a large amount of sabinene also had a large amount 

of terpinolene. 

Three trees at Paulina are of note: the high-sabinene tree discussed above, a 

high-myrcene tree, and a high-ß-phellandrene tree; this is the highest amount of 

myrcene I have found in any pine. The percentage composition of these three 

trees is as follows: 

α-pinene ß-pinene 3-carene sabinene myrcene limonene ß-phellandrene terpinoline 

1. 2.6 11.3 8.1 23.0 25.3 8.9 tr. 20.0 

2. 3.6 tr. 23.9 0.6 68.8 tr. tr. 4.0 

3. 4.6 21.1 21.2 tr. 26.0 6.8 16.1 4.1 

Are these three trees really unusual, or are there similar trees in other parts of 

the species distribution?

The three stands differed markedly in the characteristics of the frequency

distribution of four variable components: ß-pinene, 3-carene, myrcene, and 

limonene (fig. 3-2); α-pinene was only moderately variable. The frequency

distributions of the four variable components tend to be trimodal. When all 

three stands are viewed together, an approximation was made of the three 

modes and the frequency intervals that describe them (table 3-4).

The monoterpene composition types, obtained by converting the 

composition of each tree to a four-digit value (table 3-4), showed a wide range 

of 25 types (table 3-5). When the occurrence of these types was normalized for 

each stand, the large difference between the Sierra Nevada stand and the two 

Cascade stands was clearly evident (fig. 3-3,) and the substantial difference 

between the two Cascade stands was also clearly evident. That is, the types of 

composition found in the two Cascade stands were somewhat similar, but their 

frequencies were quite different. For example, type 10 was by far the most 

common type at Mt. Rose, but that type did not occur at all in the two 

Cascade stands. Likewise types 1 to 5 were very common in the Shasta 

stand, were uncommon in the Deschutes stand, and did not occur at all in 

the Mt. Rose stand. 

The coefficient of association between the stands was very low, at about 0.1, 

though one might question the use of this analysis because of the large

differences in numbers of trees in the three stands. Even without this statistic, 

the differences between stands were evident, i.e., the two Cascade stands were 

different in the frequency of types, and the Sierra Nevada stand was clearly

different from the two Cascades stands in both presence and frequency of 

compositional types as noted above. Likewise the numbers of composition 

types in the three stands were very different, with only four types at Mt. 

Rose, 13 types at Paulina, and 21 types at Mt. Shasta. 

These differences in means, ranges, and in the kinds and frequency of 

composition types suggest that there are major genetic differences between the 

Cascade and Sierra Nevada stands—probably at the gene level—and minor 

genetic differences between the two Cascade stands-probably at the allele 

frequency level. The study was limited to a very small portion of the tree's 

range. It is apparent that with such large local variation, larger numbers of trees 

were needed at both the Mt. Rose and Paulina Mountains to improve the

analyses. Obviously, too, a survey of the rest of the species distribution 

would be useful. There appears to be little relationship, based on xylem 

monoterpenes, between P. albicaulis and the other four pines of the 

subsection Cembrae. According to Mirov (1961), the monoterpenes in all

four Eurasian species are largely α-pinene and ß-pinene. 

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

Smith 19 Pine Species of California Chapter 3 

Table 3-4—Intervals in the frequency distribution of normalized percentages for the individual 

monoterpenes of P. albicaulis that were used to define the low (0), medium (1), and high (2) modes 

Monoterpene 

Mode Code ß-pinene 3-carene myrcene limonene 

value 

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

1 

Low 0 0 -3 0 - 58 0 - 10 0 

Medium 1 4 - 16 59 - 78 11 - 30 1 - 6 

High 2 17 - 100 79 - 100 31 - 100 7 - 100 

1

 Normalized percent. 

Table 3-5—Twenty-five coded types of xylem monoterpene composition of P. albicaulis, their frequency in the 125-tree sample (N),and the average actual composition of these coded types; * = trace 

Actual composition 

monoterpene 1 

No. 

Coded 

Type 2 N α-p cam ß-p car sab myr lim ß-ph γ-t ter 

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

1 0 0 1 1 1 2.5 - 2.2 56.0 

2 0 0 1 2 4 1.7 * 0.3 54.2 

3 0 0 2 0 11 2.5 0.1 0.7 49.3 

4 0 0 2 1 14 2.4 * 1.5 51.8 

5 0 0 2 2 4 2.3 * 0.6 42.3 

6 0 1 1 0 9 1.8 0.1 0.4 74.3 

7 0 1 2 1 1 1.9 0.3 0.8 60.0 

8 0 1 1 1 3 1.7 * 0.5 63.4 

9 0 1 1 2 5 1.6 0.1 0.2 61.9 

10 0 2 0 0 6 2.4 0.3 0.4 84.7 

11 0 2 0 1 29 1.9 * 0.3 85.1 

12 0 2 1 0 2 1.5 * 0.3 79.5 

13 1 0 1 0 3 3.2 * 12.3 53.8 

14 1 0 1 1 4 2.3 0.1 10.8 49.7 

15 1 0 1 2 4 6 2.6 * 11.2 43.2 

16 1 0 2 0 7 4.3 * 10.1 44.4 

17 1 0 2 1 1 2.5 * 5.4 41.1 

18 1 1 1 0 2 1.8 * 9.5 63.1 

19 1 1 0 1 3 2.5 * 8.1 67.2 

20 1 1 1 1 2 2.1 0.1 5.0 64.5 

21 1 1 1 2 1 2.7 * 6.6 60.7 

22 2 0 0 1 2 5.8 0.2 34.4 48.0 

23 2 0 1 0 3 4.2 * 19.3 47.0 

24 2 0 1 1 4 4.3 0.2 18.8 42.3 

25 2 0 1 2 1 4.9 * 21.1 26.2 

percent 3 

- 29.2 3.7 0.3 0.4 5.4 

- 28.3 9.4 * 0.5 5.6 

0.1 41.2 * 0.5 0.1 5.5 

* 34.7 3.4 0.3 0.1 6.4 

- 41.8 7.0 0.3 0.1 5.6 

- 13.8 0.2 0.5 - 8.9 

- 31.3 0.5 0.3 - 4.7 

- 23.0 3.5 0.2 0.2 7.5 

- 21.5 8.6 * 0.2 5.7 

- 4.6 0.2 0.3 0.1 6.8 

- 4.0 1.4 0.3 * 7.0 

- 12.6 0.3 0.2 - 5.5 

* 23.6 * 0.3 - 6.7 

* 23.0 4.9 1.0 * 7.6 

3.8 21.0 9.9 0.3 - 8.4 

* 35.6 * 0.3 - 5.1 

* 41.9 4.5 0.6 - 3.9 

* 17.6 * 0.4 - 7.7 

- 9.6 4.8 0.7 - 6.7 

* 16.4 3.4 0.4 - 7.8 

- 16.7 6.7 0.3 - 6.5 

- 4.5 2.1 0.2 - 4.8 

* 22.2 * 0.4 - 6.1 

* 25.7 2.9 0.6 - 5.0 

* 26.0 6.8 16.1 - 4.1 

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

ß-phellandrene, γ-terpinene, terpinoline. 2

 From left to right: ß-pinene, 3-carene, myrcene, limonene; see table 3-4 for values of code numbers. 3 Average for the normalized composition for the trees in each type. 4 One tree with 23 percent sabinene and 20 percent terpinolene. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 17 
Chapter 3 19 Pine Species of California Smith 

Figure 3-2—Frequency distribution of 

the amount of the listed monoterpenes, 

in three stands of P. albicaulis, Mt. Rose, 

Mt. Shasta, Paulina Mountains, listed on 

the right; ea

except where 

each represents n trees;▲ is average of 

ch dot is the measurement 

of one tree indicates 

set. 

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

Figure 3-3—Frequency distribution of 

26 types of monoterpene composition 

in three stands of P. albicaulis see table 3-

5 for coded and actual composition of all 

types; occurrence normalized for each 

stand. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 19 
Chapter 3 

19 Pine Species of California Smith 

#2. Pinus aristata Engelm. (bristlecone pine) P. aristata occurs in widely scattered, generally small stands of trees at high 

elevation in Colorado, Utah, Nevada, east central California, northern Arizona, 

and northern New Mexico (fig. 3-4). It is most notable for its long life; trees 

more than 4,000 years old have been found. 

Mirov (1961) sampled trees in the White Mountains of east central 

California and found them to have about 96 percent α-pinene. At that time the 

species name was Pinus aristata. Zavarin and Snajberk (1973) and Zavarin and 

others (1976) sampled trees throughout the range of P. aristata and found two 

distinct monoterpene compositions. Trees in the western portion of the range— 

including Utah, Nevada, and California—were much like those in Mirov's 

report, generally having about 95 percent α-pinene and small to trace amounts 

of several other monoterpenes. Those in the eastern portion of the range— 

including Colorado and the northern parts of Arizona and New Mexico—were 

found to have only 1 to 5 percent α-pinene and about 75 to 85 percent 3-carene 

with small amounts of minor components (table 3-6). On the basis of this 

difference and several morphological differences as well, Pinus aristata was 

divided into two species: Pinus aristata in the east and Pinus longaeva in the west 

(Zavarin and others 1976). Because P. longaeva is not listed in Griffin and 

Critchfield (1972), this review will retain the name as P. aristata, though P. 

longaeva will be used with reference to recent publications. 

Zavarin and others (1976) made a more comprehensive study and found 

some agreement with their previous work, but they also found some 

differences. Some stands within the geographic area assigned to P. aristata or P. 

longaeva had a monoterpene composition which differed markedly from that of 

either of the two species. Most notably, three stands were found well within the 

geographic area assigned to the western form, i.e., P. longaeva, that averaged 

approximately 46 percent: α-pinene and 39 percent 3-carene plus minor 

components (table 3-6). These localities were at Spring Mountain, Nevada; 

Tamarack Canyon, California; and White Mountains, California (table 3-7). 

Likewise one stand at Humphreys Peak, Arizona, had an average composition of 

about 23 percent α-pinene and 43 percent 3-carene; this same stand had usual 

amounts of limonene (10 percent), ß-phellandrene (9 percent), and ß-pinene 

(9 percent) (table 3-6). These average values, however, mask considerable 

variation which is seen by a listing of individual trees (table 3-7). 

Zavarin and others (1980, 1982) expanded their sampling in western Nevada 

and eastern California and found the earlier results to be generally correct, 

but they also found three California stands with striking differences. The 

area of Tamarack Canyon had trees typical of P. longaeva—with about 90 

percent α-pinene—as well as trees which could be classed as hybrids—with 

about 58 percent α-pinene and 27 percent 3-carene. Much the same situation 

was found in a stand at Cerro Gordo in the Inyo Mountains of southeastern 

California. Further confusing the situation was the finding by Zavarin and 

others (1980, 1982) of stands at Sentinal Peak and Telescope Peak, both in the 

mountains west of Death Valley, California, that were completely typical of 

eastern P. aristata stands with about 75-85 percent 3-carene, 5-7 percent α-pinene, 

and trace to small amounts of minor components. There were generally 10 trees per stand in those reported studies. 

It is difficult get a clear picture of separation of P. longaeva and P. aristata on 

the basis of xylem monoterpene composition by looking only at the aggregate 

data of these three reports. That is, there were stands deep in the range of P. longaeva 

that have the monoterpene composition of stands classified as P. aristata. 

Zavarin and others (1976) proposed that the most likely explanation of the 

trees classed as P. longaeva / P. aristata was a hybridizing of the two at some time 

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

Figure 3-4—Distribution of P. aristata 

(from Critchfield and Little 1966) with the 

approximate separation into P. aristata and 

P. Iongaeva (dashed line) as adapted from 

Zavarin and others (1976). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 21 
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Chapter 3 19 Pine Species of California Smith 

Table 3-6—Average xylem monoterpene composition of stands of P. aristata (aris), P. longaeva (long.), 

and mixed stands as derived from Zavarin and others (1976). See Table 3-7 for composition of trees 

classified as hybrids of the two species 

Stand Species Stands Total Monoterpenes1 

Location trees α-p cam ß-p car sab myr lim ß-ph γ-t ter

Number -----------------------------------------------percent

2

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

a long. 8 108 94.0 1.5 2.0 ** 0 0.4 1.5 0.5   

b aris. 4 43 6.0 0.1 6.0 73.1 0 2.5 4.5 3.5 0.3 3.5 

c mixed 3 12 46.0 1.1 5.0 39.1 0 2.0 4.5 1.5 0 1.3 

d aris. 3 34 4.9 0.1 3.5 71.5 0.7 1.5 7.9 4.0 0.3 3.7 

e mixed 1 4 23.0 **  9.0 43.0 0 1.2 10.5 9.0 ** 4.0 

1 α-pinene, camphene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, γ-terpinene, terpinolene. 2 a: Duschene, Utah; Mt. Helen, Utah; Cedar City, Utah; Timber Mt., Nev; Spring Mt., Nev; White 

Mtns., Calif.; Tamarach Cn., Calif.; Onion Valley, Calif. 

b: Conejos Rv., Colo; Leavenworth, Colo.; Lake Peak, N.M.; Sentinal Pk., Calif. 

c: Spring Mtn., Calif.; Tamarack Cn., Calif.; White Mtns., Calif. 

d: Fremont Pk., Ariz; Aggissiz Pk., Ariz.; Humphrey Pk., Ariz. 

e: Humphrey Pk., Ariz. 3 li d ** 

Table 3-7—Xylem monoterpene composition of individual trees classed by Zavarin and others (1976) as possible hybrids of P. aristata-P. longaeva 

Locality Monoterpene 1 

and State α-p cam ß-p car sab myr lim ß-ph γ-ter terp 

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

Spring Mts., NV 61.5 3.6 14.5 0 0.1 3.8 12.4 0.6 0 3.6 

White Mt., CA 57.2 0.5 0.7 37.7 * 0.7 0.8 0.7 0.1 1.4 

White Mt., CA 49.3 0.6 0.3 48.2 0 0 1.0 0 0 0 

Tamarack Can., CA 37.6 0.3 0.5 58.4 0 0.4 0.2 0.5 0 0 

Tamarack Can .,CA 31.1 0.6 1.5 60.0 0 1.0 0.7 2.4 0 0 

Humphreys Pk., AZ 32.5 0 4.1 48.1 * 1.1 7.9 3.7 * 2.6 

Humphreys Pk., AZ 14.3 0.2 11.5 46.1 * 1.5 9.7 11.2 * 5.5 

Humphreys Pk., AZ 19.8 0 14.5 26.2 * 1.3 13.3 18.3 * 6.1 

Humphreys Pk., AZ 24.4 0 7.1 53.4 * 1.0 9.8 2.8 * 1.4 

Lake Pk., NM 64.5 4.8 6.4 0 0 0 24.1 0 * 0 

1 Normalized: α -pinene, camphene, ß -pinene, 3-carene, sabinene, myrcene, limonene, ß -phellandrene, γ -terpinene, terpinoline. 

2 Normalized; * = trace. 

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

th 19 Pine Species of California Chapter 3 

in the past. However, an equally valid explanation was that the so-called hybrid was the older and parent tree of the three types. Zavarin and others

(1976) showed evidence of heterozygosity of 3-carene; there was no discussion 

about the heterozygosity of α-pinene. If both α-pinene and 3-carene were 

heterozygous in the mixed stands, crossing and segregation could easily produce

either high α-pinene or high 3-carene. Another factor to consider was the long 

period of time that stands have been isolated from one another so that there had 

been little opportunity for the constant mixing of alleles. It is an interesting

condition, and we may not have the final picture of P. longaeva or P. aristata. 

There was the question of tree age also. Nearly all studies of xylem 

monoterpenes of pines have been with trees less than 100 years old, although 

a few trees more than 100 years old were used in studies of P. ponderosa, 

P. lambertiana, and P. jeffreyi. I do not know of a study comparing young and 

very old P. aristata. 

#3. Pinus attenuata Lemm. (knobcone pine) P. attenuata ranges extensively in California, though a sizable portion of it

s

range does extend northward into southern Oregon (fig. 3-5). It is one of the 

group of California closed cone pines, along with P. muricata and P. radiata. P. 

attenuata was used in early pine hybridization work at the Institute of Forest

Genetics (IFG), in Placerville, Calif., in an attempt to combine its drought and

cold tolerance with the growth characteristics of P. radiata. Mirov (1961) reported

the xylem monoterpene composition of P. attenuata to be near-pure α-pinene.

Two stands were sampled in California for this study: 89 trees near Gold 

Run, Placer County, and 39 trees near Mt. Shasta, Siskiyou County (fig. 3-5). 

The average composition of both stands was nearly identical, 94 to 96 percent 

α-pinene with small to trace amounts of camphene, ß-pinene, 3-carene, 

myrcene, ß-phellandrene, and terpinolene (table 3-8). The standard deviations 

were extremely low, indicating low variability in the trees in both stands. That 

the two stands were nearly identical in monoterpenes, though about 200 miles 

apart, suggests that the minor components are products of biosynthesis or

isomerization and are not caused by external environmental factors. The 

frequency distributions of individual monoterpenes were very similar for the 

two stands (fig. 3-6). There was little or no difference in composition between a 

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

Bannister and others (1959) examined the resin from 16 P. attenuata that 

were from seed collected in California but grown in New Zealand. Nine of the 

trees were about 45 years old, and seven were 5 years old. The composition of

the 45-year-old trees was very much like those of the trees in this study, though 

trace to small amounts of some of the components were not reported (table 3-8). 

The composition of the 5-year-old trees was slightly different with an average 

of 5.2 percent 3-carene. This is one of the few instances in which very young 

trees were sampled in the study of the 19 species. One would suspect either that 

the unusually high 3-carene was an age factor which will not persist, or that the young trees were progeny of a particular tree which was inclined to contain 

small amounts of 3-carene, as noted by the listing in table 3-9. Also, one tree at 

Mt. Shasta had about 4 percent 3-carene (table 3-9).

Anderson and others (1969) used cut logs from trees near Mt. Shasta and 

extracted the resin from the sapwood by chipping the xylem in a mill and 

extracting the volatiles by steam distillation of the chipped xylem. They found 

radically different monoterpene composition: 19 percent camphene, 49 perce

nt 

3-carene, 6 percent myrcene, 6 percent limonene, 17 percent ß-phellandrene, 

and 8 percent unidentified. These results indicate that either composition is 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 23 
---------------------------- 

Chapter 3 19 Pine Species of California Smith 

Figure 3-5—Distribution of Pinus attenuata (from Griffin and Critchfield 1972); 

and the location of the Mt. Shasta (B) and 

Gold Run (A) stands; is location of 

P. radiata. 

Table 3-8—Average xylem monoterpene composition of four stands of P. attenuata; Mt. Shasta and 

Gold Run trees were from this study; data from two stands in New Zealand trees were taken from 

Williams and Bannister (1962) 

Monoterpene1 

Source of Age of 

trees trees N α-p cam ß-p ß-car myr lim ß-ph ter 

yr percent 2 --------------------------------------

Gold Run 20-40 89 96.1 0.1 1.8 0.2 0.8 0.5 0.6 * 

Mt. Shasta > 40 39 94.2 0.3 2.5 0.4 0.9 0.5 1.1 * 

New Zealand 3 45 9 95.5 - 4.5 - - - - -

New Zealand 3 5 7 92.5 - 2.1 5.2 - - -

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

 Normalized, * = trace, - = zero. 3

 From seed collected in California. 

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

Smith 19 Pine Species of California Chapter 3 

Table 3-9—Xylem monoterpene composition of selected individual trees of P. attenuata 

Monoterpene 1 

Source α-p cam ß-p car myr lim ß-ph ter 

percent

2

-----

Mt. Shasta 95.8 0.3 1.5 0.2 0.8 0.5 0.7 * 

Mt. Shasta 91.5 0.3 2.0 4.3 0.6 0.1 0.8 0.8 

Gold Run 97.1 * 1.0 0.2 0.8 0.4 0.3 -

Gold Run 94.3 0.1 2.5 * 1.0 0.8 1.3 -

Gold Run 94.8 * 1.7 1.8 0.7 0.4 0.6 -

1 α-pinene, camphene, ß-pinene, 3-carene, myrcene, limonene, ß-phellandrene, terpinoline. 2

 Normalized; * = trace, - = zero. 

Figure 3-6—Frequency distribution of the 

amount of the noted monoterpenes of Pinus 

attenuata in two stands: Gold Run (A), Mt. 

measurement of one tree except where 

indicates each represents n trees; ▲ is average of set. 

Shasta (B), listed on the right; each dot is 

. 

(fig. 3-6 continues on next 2 pages). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 25 
Chapter 3 19 Pine Species of California Smith

26 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 27 
Chapter 3 

19 Pine Species of California Smith 

changed in the tree as the resin is deposited deep in the sapwood or gross

changes were caused by the extraction process. Studies with other pines showed

little or no change in composition of annual growth rings. 

#4. Pinus balfouriana Grev. and Balf. (foxtail pine) 

P. balfouriana is limited to two high-elevation centers in California: a northern population in the Klamath Mountains, and a southern population in the southern Sierra Nevada, largely in Sequoia-Kings Canyon National Park (fig. 3-

7). The two populations appear to be distinct in several morphological 

characteristics (Mastrogiuseppe and Mastrogiuseppe (1980). Mirov (1961)

reported the xylem monoterpene composition of the northern source to be 

about 90 percent α-pinene, plus 2 percent ß-pinene, and 2 percent limonene. He 

found the southern source to be about 98 percent α-pinene and without 

limonene. Mirov's northern sample was an aggregate from 70 trees and the 

southern sample from 20 trees. 

More recently, the xylem monoterpene composition of the two populations 

was reported to be slightly different by Mastrogiuseppe and Mastrogiuseppe

(1980) (table 3-10). Both populations were high in α-pinene, but the northern 

population had about 9 percent limonene whereas the southern population had 

only about 1 percent limonene (table 3-10). Numbers of trees sampled were not 

given by Mastrogiuseppe and Mastrogiuseppe, nor were ranges given for 

components. Thus, one cannot tell whether the 9 percent limonene in the 

northern source was the result of most trees with small amounts of limonene, 

or most trees without limonene and some trees with substantial amounts. If it 

was the latter condition, then one might assume that limonene might be 

controlled by a gene, and the two populations were genetically different. If it 

was the former condition, i.e., most trees with small amounts of limonene, then 

we might assume that the difference in limonene was due to isomerization or 

environmental factors and that the two sources were not different. 

Snajberk and others (1979) sampled 30 trees each in the northern and the 

southern populations and found essentially the same difference as 

Mastrogiuseppe and Mastrogiuseppe (1980); i.e., the northern population had 

about 8 percent limonene while the southern had less than 1 percent. Snajberk

and others (1979) reported, but did not substantiate, that there was considerable 

overlap in the frequency distribution of limonene in the two areas, and also 

reported a large S.D. Thus, it appeared to me (from the S.D.) that there was a 

possibility of the northern population having some trees with very small amounts 

of limonene and some with moderate amounts, possibly 10 to 15 percent. If so,

the difference in limonene between the two populations could be genetic. A 

display of the frequency distributions of the components would have been 

helpful. Both papers did accord subspecies status to the two populations on the

basis of monoterpenes and a number of morphological features.

The composition of the southern population is quite similar to P. aristata in 

that region (see species #2 of this chapter), which is sometimes mistaken for P. 

balfouriana. The two species are allopatric but grow near each other. 

#5. Pinus contorta Dougl. ex Laud (lodgepole pine) 

The species P. contorta is the most widely distributed pine in North America 

(fig. 3-8); worldwide, it is exceeded only by Scots pine (P. sylvestris L.), which is 

widely distributed across Eurasia. Ecologically, P. contorta is of prime 

significance because of the tremendous range and area it occupies. This species 

has several variable characteristics that have caused it to be variously

subdivided into a number of varieties. The most recent classification (Critchfield

1980) proposed five races: Rocky Mountain-Intermountain (var. latifolia 

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

Smith 19 Pine Species of California Chapter 3 

Figure 3-7—Distribution of P. balfouriana in California, taken from Griffin and 

Critchfield (1972); (A) is Klamath Mtns. 

population, (B) is Sierra Nevada population. 

Table 3-10—Average xylem monoterpene composition of northern and southern populations of 

P. balfouriana; adapted from Mastrogiuseppe and Mastrogiuseppe (1980); number of trees sampled not given 

Population Monoterpene 1 

α-p cam ß-p 3-car myr lira ß-ph ter p-cy 

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

Northern 85.4 1.0 2.2 6.2 0.6 9.3 0.2 0.9 0.2 

Southern 94.8 1.0 1.9 0.1 0.4 1.2 0.1 0.2 0.4 

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

para-cymene. 

2

 Normalized. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 29 
Chapter 3 19 Pine Species of California Smith 

Figure 3-8—Distribution of Pinus contorta 

(taken from Critchfield and Little 1966) and 

the locations of sampled stands; see table 3-

11 for specific location of stands. 

Table 3-11—Location of stands of P. contorta, number of trees tapped for resin, and number and percent of 

trees producing a sample of resin 

Trees 

Stand National Forest Locality tapped Trees yielding resin 

number number percent 

1 Inyo, Calif. Deadman Summit 100 87 87 

2 Eldorado, Calif. Ralston Peak 120 100 83 

3 Lassen, Calif. McCoy Flat 120 67 56 

4 Modoc, Calif. Homestead Flat 137 51 37 

5 Winema, Oreg. Buckeye Flat 140 85 61 

6 Wallowa-Whitman, Oreg. Granite Summit 56 37 66 

7 Targhee, Idaho Island Park 89 47 53 

8 Flathead, Mont. Hungry Horse 36 15 42 

9 Arapaho, Colo. Buffalo Peak 111 92 83 

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

(Total) 909 581 (Av)64 

(Av)=average 

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

th 19 Pine Species of California Chapter 3 

[Engelm.] Critchfield), Sierra-Cascade (var. murrayana [Balf.] Critchfield),

Coastal (var. contorta), Mendocino County White Plains (var. bolanderi Parl. 

Vasey), and Del Norte County (not named).

One of the variable characteristics of P. contorta was the monoterpene 

composition of its xylem resin. Mirov (1961) reported the monoterpene fraction

of the xylem resin from trees in the central Sierra Nevada to be composed 

almost entirely of ß-phellandrene with small to trace amounts of other 

monoterpenes. I looked at trees in the same area and concurred with Mirov that 

ß-phellandrene was the major monoterpene, averaging about 70 percent of the

terpene fraction (Smith 1964c). I also found as much as 15 percent ß-pinene and 

3-carene in some trees, and rather consistent amounts—ranging from 3 to 7 percent—of α-pinene, sabinene, myrcene, and limonene in nearly all trees. In a

study of P. contorta in different locations in the Sierra Nevada, little difference 

was found in average composition over the rather wide geographic region 

(Smith 1967b). However, a few trees were found with 3-carene greater than 20 

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

sample and one at 20 feet (table 8-1). Zavarin and others (1969) sampled 12 trees 

in the Sierra Nevada and found that all but one fell within the range I reported 

in 1967. The one tree that was different had nearly equal amounts of 3-carene 

and ß-phellandrene. Lotan and Joye (1970) analyzed the resin from 11 trees in 

southwest Montana and found a much different composition and much greater

variation than that found in the Sierra Nevada. In the Montana trees, ß- phellandrene ranged from 8 to 83 percent, ß-pinene from 6 to 58 percent, 3-carene from 2 to almost 60 percent, and α-pinene from 4 to 50 percent. 

Mirov (1956) reported that P. contorta and P. banksiana appeared to

interbreed in a broad area in central Alberta, Canada, as indicated by the xylem monoterpene composition. Such trees show the monoterpene characteristics of 

both parents, i.e., fairly large amounts of ß-pinene (P. banksiana) and ß- phellandrene (P. contorta). Additional reports of introgression or hybridization 

of P. contorta and P. banksiana as indicated by monoterpene composition were

made by Smith (1967a), Zavarin and others (1969), and Lotan and Joye (1970).

Cole and others (1981) extracted the monoterpenes from xylem of selected 

trees at three intervals during the most active portion of the growing season on 

the Cache National Forest in Utah. The proportional amount of the total monoterpenes varied somewhat, but not greatly, over the sampling period, but 

the normalized composition varied very little with about 14 percent ß-pinene, 

56 percent ß-phellandrene, and 30 percent 3-carene plus myrcene and other 

minor components. 

A Range-Wide Study 

The following discussion of a range-wide study of the xylem monoterpenes is

adapted from Smith (1983) with additional data. Nine nearly pure stands of P.

contorta were sampled in five western states (fig. 3-8) (table 3-11). Stands #1 to

#5 were in the region usually assigned to var. murrayana, and stands #6 to #9

in the region usually assigned to var. latifolia. No stands were in regions

assigned to var. contorta, or var. bolanderi. The procedures used are those

given in Chapter 2.

Quantity of Resin Flow. Resin was obtained from as many as 87 percent of the 

trees tapped in the Inyo stand, #1, and from as few as 37 percent of the trees 

tapped in the Modoc stand, #5 (table 3-11). The amount of resin that flows from 

each tap varied from more than 4 cc to 0 cc with many less than 0.1 cc. This 

variation in quantity of resin flow between trees was also found in a study of P. 

ponderosa (Smith 1977) and was studied or observed for other species of pine as 

well. The low flow in P. contorta might be attributed to cooler temperatures at 

the higher elevations; however, the flow of resin from P. contorta was much less 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 31 
Chapter 3 

19 Pine Species of California Smith 

than that from P. washoensis. Forty P. washoensis were tapped at the same 

general location and at the same time as the P. contorta in the Modoc stand. 

Only 37 percent of the P. contorta yielded resin, whereas 98 percent of the P. 

washoensis yielded resin and the amount per tree ranged from 2 to 5 cc. Monoterpene Components. The average for each monoterpene component in each 

of the nine stands showed appreciable variation between and within stands in 

three components: ß-pinene, 3-carene, and ß-phellandrene (table 3-12, fig. 3-9). 

All other components generally occurred at rather constant and relatively small 

amounts: α-pinene, 3 to 8 percent, with a few trees greater than 10 percent; 

camphene, less than 1 percent; sabinene, less than 2 percent; myrcene, 3 to 4 

percent; α-phellandrene, less than 2 percent; and terpinolene, less than 1 

percent. Limonene was almost always a minor component, ranging from 0 to 3 

percent in most trees, but in a few trees it was 5 to 10 percent. There was a 

possible trace of α-thujene which elutes near the trailing edge of α-pinene. 

Lotan and Joye (1970) reported trace amounts of p-cymene, allo-ocimene, and 

γ-terpinene, but did not report sabinene and α-phellandrene. It is difficult to 

assess the value of minor components in determining differences within and

between species and varieties. Such differences could be real or products of 

sampling and analysis. It is possible that the genetic structure for ßphellandrene is the same in all trees, very likely two additive alleles at a single locus. It is further possible that most of the variation is caused by

differences in the genetic structure for ß-pinene and 3-carene, by 

combinations of the two, and by other modifying factors such as isomerization. 

Stands #1 to #5, in areas assigned to var. murrayana, were quite similar in 

average stand composition (table 3-12); but stand #9, in an area assigned to var.

latifolia, was similar to stands #1 to #5 and to those described by Cole and others 

(1981). Therefore, average stand composition did not follow the variety assignment. 

Stands #6 to #8, in areas assigned to var. latifolia, differed from each other 

appreciably in average stand composition; they also differed greatly from 

stands #1 to #5 and stand #9. Again, average composition did not parallel variety

assignment. As one proceeds from stands #6 to #7 to #8, ß-pinene increased and ß- phellandrene decreased. No sharp gradations are discernible in stands #1 to #5. 

Composition Types 

The frequency distribution of ß-pinene, 3-carene, and ß-phellandrene (fig. 3-9),

had a tendency to be trimodal, and three levels of the percentages were assigned

(table 3-13). When actual composition was converted to coded composition,

using prescribed intervals (table 3-13), 15 composition types were defined (table

3-14). The coefficients of association (table 3-15) were calculated from the 

frequency of composition types (fig. 3-10). These coefficients clearly fell into 

three groups. • A southweste

rn type was composed of seven stands; five of these— 

Inyo, Eldorado, Lassen, Modoc, Winema—were in the Sierra 

NevadaCascade and were in the region assigned to var. murrayana. 

The other two stands that have a strong association with the

southwestern stands—Wallowa-Whitman and Arapaho—were in 

quite different parts of the Rocky Mountains, a region usually assigned 

to var. latifolia. All seven stands were closely aligned by average 

composition (table 3-12) by types of composition (fig. 3-10), and by

coefficients of association (table 3-15). The Wallowa-Whitman stand 

did appear to be slightly transitional between the southwestern and 

central type. It had strong coefficients of association with the Winema 

and Arapaho stands, but associations with the other southwestern 

stands were only moderate. 

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

Figure 3-9—Frequency distribution of 

the amount of three xylem monoterpenes of P. contorta in stands in the eight 

listed National Forests; each dot is 

measurement of one tree; ▲ is average 

of set. 

(fig. 3-9 continues on next 2 pages) 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 33 
Chapter 3 19 Pine Species of California Smith

34 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 35 
-------------------------

Chapter 3 19 Pine Species of California Smith 

Figure 3-10—Distribution of 15 types 

of resin composition (numbered) in 

stands of P. contorta in the eight listed 

National Forests; distribution was normalized for each stand, see Table 3-14 

for approximate composition. 

Table 3-12—Average monoterpene composition of stands of P. contorta on nine national forests; see 

Figure 3-8 and Table 3-11 for stand information 

Stand Trees National Monoterpene 1 

Forest 2 α-p ß-p car sab myr lim ß-ph ter 

----number---- ------------------------------------------percent

3

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

1 87 Inyo 5.2 6.8 8.8 1.6 3.7 1.5 71.9 * 

2 100 Eld 4.7 3.9 11.7 2.2 3.6 1.4 71.1 * 

3 67 Las 4.8 3.8 6.0 1.8 3.9 1.0 77.7 * 

5 85 Win 5.7 7.5 4.6 2.2 3.6 1.2 75.1 * 

4 51 Mod 4.7 6.3 9.5 1.5 3.8 2.1 70.3 * 

9 92 Ara 5.6 8.7 9.7 2.5 1.9 1.6 69.2 0.3 

6 37 W-W 5.9 10.7 7.4 1.7 3.4 1.5 66.3 * 

7 47 Tar 6.5 19.8 8.7 1.2 3.3 2.9 61.0 * 

8 15 Fla 7.2 22.4 6.6 1.6 3.1 1.4 56.7 * 

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

 Inyo, Eldorado, Lassen, Winema, Modoc, Arapho, Wallowa-Whitman, Targhee, Flathead. 3

 Normalized; * = trace; also trace amounts of α-phellandrene, α-thujene, γ-terpinene in many trees. 

Table 3-13—Percent intervals of individual monoterpenes of P. contorta used to 

define the low, medium, and high mode of the frequency distribution of three monoterpenes, taken from Smith (1983) 

Code value 

Component 0 1 2 

-------------------------Intervals in percent 

ß-Pinene 0-10 10.1-30 30.1-100 

3-Carene 0-10 10.1-30 30.1-100 

ß-Phellandrene 0-52 52.1-70 70.1-100 

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

Table 3-14—Fifteen coded types of composition of P. contorta and their actual 

average composition, in nine stands in nine National Forests' 1 in western United 

States, partially adapted from Smith (1983) 

Composition Composition 2 

Coded Actual 

Number ------------------------------ percent

 3-----------------------------

1 002 5 8 73 

2 102 13 2 73 

3 012 4 13 72 

4 001 9 9 67 

5 101 19 1 66 

6 201 33 1 54 

7 011 6 22 59 

8 111 17 12 59 

9 021 1 35 52 

10 100 25 7 49 

11 200 43 2 43 

12 010 9 27 47 

13 110 18 25 47 

14 020 1 42 45 

15 120 15 31 43 

1 Winema, Lassen, Modoc, Eldorado, Inyo, Wallowa-Whitman, Arapaho, Targhee, 

Flathead. 

2 From left to right: ß-pinene, 3-carene, ß-phellandrene; minor components omitted. 

3 Normalized for each composition; minor components comprise the remainder of the 100 

pct; see table 3-12 for approximate amounts. Normalized for each plot. 

Table 3-15—Coefficients of association between stands of P. contorta based on types of monoterpene 

composition 

Stand number 1 

and National Forest 

Eld Las Mod Win W-W Ara Tar Fh 

1 Inyo .81 .72 .58 .67 .67 .84 .03 .00 

2 Eldorado .83 .74 .69 .53 .69 .01 .00 

3 Lassen .66 .94 .68 .67 .01 .00 

4 Modoc .58 .49 .71 .03 .00 

5 Winema .81 .73 .05 .00 

6 Wallowa-Whitman .86 .22 .00 

9 Arapaho .38 .05 

7 Targhee .46 

8 Flathead 

1

 See figure 3-8 for locations of stands. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 37 
Chapter 3 

19 Pine Species of California Smith 

stand was poorly associated with stands in the southwestern type and

with the northeastern type, though it was associated more strongly with 

the northeastern type. The stand thus appeared to be transitional. 

• A northeastern type was represented by only one stand, the Flathead, 

which was poorly associated with the Targhee stand, and was not 

associated at all with the southwestern stands. The Targhee and the

Flathead stands had much of the same types of composition but differed 

in their frequencies.

The southwestern region was characterized by the 002 composition type. This 

type was also common in the central region, but it was not the common type in

the northeastern region, though it did occur there, but not commonly. The 101 

type was most common in the northeastern region, fairly common in the central 

region, and only moderately common in the southwestern region. The 110 type 

was fairly common in the northeastern region, rare in the central region, and 

absent in the southwestern region. The 012 type was fairly common in the 

southwestern and central regions but was absent in the northeastern region. 

Summary P. contorta was sampled for xylem 

monoterpenes in areas assigned to var. 

murrayana and var. latifolia; areas assigned to other varieties were not sampled. 

There was considerable local variation in all stands, particularly in α-pinene, ßpinene, 3-carene, and ß-phellandrene. All stands from the region assigned to 

var. murrayana had considerable local variation. However, they were similar in 

average composition and were strongly associated by types of composition.

Much like P. ponderosa, as will be shown later in this chapter, there was

surprising strong association between stands where local variation was large

and where one would expect greater differences. Stands from the region 

assigned to var. latifolia were not similar in average composition and were not

strongly associated by types of composition. Stands in northern Montana and 

southeastern Idaho differed sharply from the var. murrayana stands both in 

average composition and in types of composition; but the two stands also 

differed sharply from each other. However, stands in northern Colorado and 

eastern Oregon were most strongly associated with the typical var. murrayana 

stands, though they tended to be slightly intermediate between the var. 

murrayana stands and the other two var. latifolia stands. Limonene was about 2 percent in all stands and had only small variation. If the increase in ß-pinene was indicative of the influence of P. banksiana on P. contorta, then the influence 

of P. banksiana extends far beyond the zone of introgression in Alberta, Canada, 

as proposed by Mirov (1956). 

#6. Pinus coulteri D. Don (Coulter pine) P. coulteri is limited to the coastal mountains of California from Mt. Diablo in 

the north to the northwest portion of Baja California in the south (fig. 3-11). It 

often occurs with P. jeffreyi in southern California with which it can hybridize naturally; but natural hybrids are rare. Smith (1977) reported a possible hybrid 

of P. coulteri and P. ponderosa in the San Bernardino National Forest. P. coulteri 

and the natural hybrid of Jeffrey x Coulter were heavily used in the breeding 

program at the Institute of Forest Genetics (IFG) from about 1940 to 1970 

because P. coulteri grows well under dry conditions and has a good growth 

rate. However, the tree generally has heavy limbs and sometimes poor 

commercial form. P. coulteri is one of the three big-cone pines in California; the 

other two are P. sabiniana and P. torreyana.

Mirov (1961) analyzed trees growing at IFG for terpenes and reported 

the xylem volatiles to be about 5 percent heptane, 33 percent α-pinene, 33 

percent ß-phellandrene, and 10 percent undecane. Smith (1967b) analyzed 20 

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

Figure 3-11—Distribution of P. coulteri in 

California (taken from Griffin and Critchfield 

1972) and the county of location of stands 

used for sampling mature trees. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 39 
Chapter 3 

19 Pine Species of California Smith 

trees at IFG and found a considerable range in α-pinene, myrcene and bphellandrene with measurable amounts of several other monoterpenes as well as heptane (table 3-16). Little or no difference in composition was found between 

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

More recently, I examined two sets of populations. One set was 64 trees, 

greater than 40 years old, in nine natural stands from throughout the range; the 

other set was 105 2-year-old seedlings, growing at IFG, from three sources: Mt. 

Diablo, Figueroa Mountain, and San Diego County. There were 35 trees from 

each of the three sources. This is one of the few times that very young trees are 

reported in the 19 pines of California. 

The results of the analysis of the 64 trees from natural stands (table 3-17) 

showed an average composition fairly similar to the earlier results (Smith 1967b). 

The variation and the small numbers of trees at the nine locations prohibited any 

firm conclusion about local and regional characteristics. All localities had 

considerable variation in α-pinene, myrcene, and ß-phellandrene, and there was 

considerable variation in composition among the trees (table 3-18). 

The only obvious regional difference was generally higher levels of α­

pinene and sabinene in the north along with lower ß-phellandrene. However, 

larger sampling was needed. The frequency distribution of the aggregate of 64 

trees showed large variation in several components and suggested a trimodal 

distribution for α-pinene, undecane, myrcene, limonene, and ß-phellandrene 

(fig. 3-12). But the limited data did not permit an analysis of types of 

composition. 

The composition of P. coulteri was distinctive in having large amounts of α­

pinene, myrcene, and ß-phellandrene; as noted earlier, the largest amounts of 

myrcene found in pine were found in P. albicaulis. I know of no other pine in the 

United States which had such a distinctive composition in its xylem resin as P. 

coulteri. It did, however, resemble some sources of P. patula in Mexico (see 

Chapter 4, #70). In some respects this composition might suggest that P. coulteri 

was a link between P. ponderosa and the big-cone pines. 

The analysis of the 2-year-old seedlings gave quite different and surprising 

results (table 3-19). Although the averages of these three plots did not differ 

greatly in composition, they differed greatly from the composition of the old, 

naturally growing trees (tables 3-16 and 3-17). There was a very strong juvenile 

effect, because the amounts of several monoterpenes were quite different in 

young seedlings than in mature trees: heptane, nonane, undecane, camphene, 

sabinene, myrcene, limonene, and ß-phellandrene were much higher in mature 

trees than in 2-year-old seedlings, while α-pinene, ß-pinene, and 3-carene were 

much lower in mature trees. As will be shown later in Chapter 5, this same 

general condition was found at a much lesser degree when comparing young 

and old P. ponderosa and has been called the juvenile factor. One can only 

speculate that the increase in minor components like camphene was a reflection 

of cumulative isomerization with age. The large differences in major 

components like myrcene and ß-phellandrene could be caused by either a 

strong juvenile effect or changes in the gene-controlled synthesis or both, 

though large-scale, long-term isomerization was a possibility. 

The frequency distribution of the three nursery sets of 2-year-old seedlings 

indicated a trimodal distribution for α-pinene, myrcene, and ß-phellandrene 

(fig. 3-13). Though this condition usually warranted coding and tree-type 

classification, as well as distribution, the presence of such a strong, and presumably temporary, juvenile effect would not yield meaningful results. 

In summary, and based on limited local sampling, local populations of 

mature P. coulteri varied considerably in α-pinene, myrcene, and ßphellandrene. However, there was no strong suggestion of sharp regional 

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

Smith 19 Pine Species of California Chapter 3 

Table 3-16—Average xylem monoterpene composition of 20 P. coulteri growing at the Institute of 

Forest Genetics (IFG) [taken from Smith (1967b)], and composition of individual trees selected to 

illustrate the range of composition 

Monoterpene 1 

Source of 

trees 2 N hep non α-p und cam ß-p car sab myr lim ß-ph ter 

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

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

20 1.3 1.3 36.5 2.0 1.9 2.1 0.5 1.6 20.3 3.8 28.1 0.3 

17 1 0.6 0.9 25.2 * 2.2 2.5 1.1 1.8 41.4 4.4 19.9 

17 1 5.9 3.2 32.4 * 5.7 1.9 0.3 0.3 16.2 3.0 29.4 0 

18 1 0.8 1.1 51.0 * 1.9 1.9 0.2 5.3 5.7 4.8 26.0 1.3 

18 1 1.9 1.7 33.2 3.8 0.2 1.7 0.5 7.6 15.9 2.6 26.8 4.0 

19 1 0.6 1.2 29.9 3.6 0.9 2.1 0.6 0.9 16.5 9.0 34.7 

1 Heptane, nonane, α-pinene, undecane, camphene, ß-pinene, 3-carene, sabinene, myrcene, 

limonene, ß-phellandrene, terpinolene. 

2 17 = Los Angeles County; 18 = Mount Diablo; 19 = unknown; X = all sources. 

3 Normalized; * = trace. 

Table 3-17—Average xylem monoterpene composition of 9 stands of P. coulteri in California, the general average for all stands totalling 64 trees, and the maximum and minimum for the aggregate of all trees 

Monoterpene 1 

County Trees hep non α-p und cam ß-p car sab myr lim ß-ph ter 

no. -----percent 2 ---------------------------------------------------

Contra Costa 3 1.7 1.4 41.5 2.7 0.8 1.9 0.2 4.8 14.2 3.8 25.1 0.4 

Monterey 4 * 1.3 29.5 * 5.4 0.9 0 1.2 20.0 5.8 34.6 0.8 

Santa Barbara 5 1.8 1.1 37.2 * 4.4 1.1 * 0.4 18.7 5.1 30.0 * 

Los Angeles 4 2.6 1.8 28.4 1.2 3.3 1.9 0.5 0.8 29.9 3.3 26.1 0 

Riverside 15 * 1.3 23.1 * 5.2 * 0 0.5 20.6 6.6 41.3 0.8 

San Diego 9 * 1.2 26.2 * 4.8 0.9 0 0.5 19.2 4.4 42.4 0.2 

San Diego 7 1.1 1.4 40.0 3.2 1.0 2.2 0.4 1.3 18.0 3.4 27.2 0.5 

Unknown 6 0.9 1.0 31.5 1.3 2.7 1.9 0.7 1.0 22.7 4.9 31.7 0 

Several3 11 * 1.0 28.7 0 4.5 1.4 0 1.4 22.0 5.5 34.4 1.0 

(64) 0.6 1.2 29.8 1.7 1.4 1.4 0.2 1.0 20.7 5.0 34.8 0.4 

Max 6 4 51 8 6 3 2 6 42 19 59 

Min 0 0 12 0 0 0 0 0 0 1 20 

1

 Heptane, nonane, α-pinene, undecane, camphene, ß -pinene, 3-carene, sabinene, myrcene, 

limonene, ß-phellandrene, terpinolene. 2 Normalized; * = trace. 3

 These trees are growing in an Institute of Forest Genetics (IFG) arboretum from seed collected from 

unknown sources. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 41 
Chapter 3 

Figure 3-12—Frequency distribution of 

the amount of the noted monoterpenes 

in the aggregate of 64 mature trees in 

nine stands of P coulteri; each dot is measurement of one tree except where. 

indicates each represents n trees; ▲ is 

average of set. 

. 

(continues on next page). 

42 

19 Pine Species of California Smith 

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

Table 3-18—Xylem monoterpene composition of individual P. coulteri selected to show the range in 

composition in California 

County Monoterpene 1

source N hep mon α-p und cam ß-p 3-car sab myr lim ß-ph ter 

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

2 ---------------------------------------------------

Contra Costa 1 0.8 1.1 51.0 - 1.9 1.9 0.2 5.3 5.7 4.8 26.0 1.3 

Contra Costa 1 2.4 1.5 40.3 4.3 0.4 2.1 * 1.5 21.0 3.9 22.5 * 

Los Angeles 1 0.6 1.3 26.8 - 4.4 1.7 0.3 0.5 37.9 3.4 22.8 -

San Diago 1 * 0.6 23.6 5.1 * 1.2 * 0.6 24.2 2.6 42.1 -

Contra Costa 1 * 0.8 40.7 4.4 * 1.6 * 2.4 6.9 4.5 36.4 -

Unknown 1 1.5 1.5 52.2 4.0 * 1.2 - 0.3 3.4 2.0 33.6 * 

Unknown 1 * 1.7 11.8 5.1 * 0.6 - 0.7 17.3 2.8 59.2 * 

Unknown 1 * 0.4 19.4 5.4 - 0.4 - 0.6 25.9 14.2 33.9 * 

Unknown 1 * 1.9 15.5 4.4 - 0.5 - 0.7 33.0 3.0 40.0 * 

1

 Heptane, nonane, α-pinene, undecane, camphene, ß-pinene, 3-carene, sabinene, myrcene 

limonene, ß-phellandrene, terpinolene. 2

 Normalized; * = trace, - = zero. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 43 
Chapter 3 19 Pine Species of California Smith 

Table 3-19—Average xylem monoterpene composition of three sets of 2-year-old nursery stock of 

P. coulteri, of the aggregate of the three sets, and of the aggregate of 64 trees in nine older stands 

Monoterpene 1 

Source2 N hep non α-p und cam ß-p car sab myr lim ß-ph ter 

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

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

1 35 * 0.4 64.7 0 0.2 3.5 4.8 0.4 0.7 0.8 24.1 0.3 

2 35 * 0.5 67.3 0 0.1 4.7 4.9 0.3 0.7 0.8 20.4 0.4 

3 35 * 0.4 64.8 0 0.1 3.9 3.9 0.5 0.8 1.1 24.0 0.3 

4 105 * 0.4 65.6 0 0.1 4.1 4.5 0.4 0.7 0.9 22.8 0.4 

5 64 1.6 1.2 29.8 1.7 1.4 1.4 0.2 1.0 20.7 5.0 34.8 0.4 

1

 Heptane, nonane, α-pinene, undecane, camphene, ß-pinene, 3-carene, sabinene, myrcene, 

limonene, ß-phellandrene, terpinolene. 

2 1 = Mount Diablo, 2 = Figueroa Mtn., 3 = San Diego County, 4 =1+2+3, 5 = average of 64 mature trees 

from nine stands 

3 Normalized; * = trace.. 

Figure 3-13—Frequency distribution 

of the amount of the noted monoterpenes in three sets of 2- year-old 

seedlings of P. coulteri of seed collected 

at the three locations listed on the right; 

each dot is measurement of one tree 

except where indicates each represents n trees; ▲is average of set.

(fig. 3-13 continues on next 3 pages). 

44 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 45 
Chapter 3 19 Pine Species of California Smith

46 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 47 
Chapter 3 

19 Pine Species of California Smith 

• A central type was represented by only one stand, the Targhee. This 

differences. Examination of 2-year-old seedlings showed a very strong 

juvenile effect. However, all data suggested gene control of α-pinene, 

myrcene, and b-phellandrene. The small amounts of the other 

monoterpenes and the related hydrocarbons heptane and undecane were 

probably not controlled by genes but were products of isomerization or 

were by-products of biosynthesis. The monoterpene composition of P. 

coulteri was totally different from that of the other two big-cone pines, P. 

torreyana and P. sabiniana; both are discussed later in this chapter. 

#7. Pinus edulis Engelm. (Colorado pinyon pine) P. edulis is widely distributed in the southern Rocky Mountains, primarily in 

Utah, Colorado, Arizona, and New Mexico (fig. 3-14). In California, an isolated 

stand is located in the New York Mountains on the eastern edge of the Mojave 

Desert. The identity of this stand of P. edulis in California was uncertain for a 

long time, but quite recently it was determined to be P. edulis (Des Lauriers and 

Ikeda 1986). Des Lauriers and Ikeda found—both by number of needles per 

fascicle and number of resin canals—that the trees at the highest elevation in 

the New York Mountains are P. edulis; those at the lowest elevation are P. 

monophylla; and those at intermediate elevation could be called a hybrid of the 

two species. Des Lauriers and Ikeda did not analyze xylem monoterpenes of 

any of the three groups of trees. Thus, P. edulis was found in California, albeit in 

one isolated and restricted locality in the Mojave Desert. 

Mirov (1961) reported the monoterpene portion of xylem resin of P. edulis 

to be 81 percent α-pinene, 4 percent myrcene, 11 percent 3-carene, 4 percent 

limonene, 4 percent terpinolene, 4 percent an unknown monoterpene, and a 

substantial amount of ethyl caprylate. He attributes part of the fragrance of 

pinyon resin to ethyl caprylate. 

Snajberk and Zavarin (1975) analyzed the resin of trees from New Mexico 

and Utah and found the monoterpene composition to be very much like that 

described in Mirov's report. In addition, they reported small to trace amounts 

of camphene, sabinene, ß-pinene, and ocimene. 

More recently Zavarin and others (1989) made a more thorough study of 

the full range P. edulis. Eighteen stands of about 10 trees each were sampled in 

Utah, Colorado, New Mexico, Texas, and Arizona. Through the use of 

dendrograms, Zavarin and others (1989) divided P. edulis into two forms: a 

southern form in southeastern Arizona and southwestern New Mexico, called 

Apache, typified by plot #34 in Grant County, New Mexico (table 3-20), and a 

northern form in the major portion of the tree's range north of the southern form. 

The northern form is typified by stand #14 (table 3-20). Zavarin and others (1989) 

also listed the frequency distribution for some of the individual components. 

From the range and average values (table 3-20) and from the frequency 

distribution of individual components, it seemed that a sample larger than 10 

trees per stand was needed to characterize the monoterpene composition of P. 

edulis. When the frequencies of individual tree measurements were examined 

(Zavarin and others 1989), it appeared that camphene, α-pinene, and limonene 

were generally higher in the northern form, and sabinene and 3-carene were 

generally higher in the southern form; however, there was a very strong 

overlap in the occurrence of individual components in the northern and 

southern forms. It would be interesting to see what the frequency 

distribution would be for a 50- to 100-tree stand in each of the two areas of 

the northern and southern forms. 

Judging by the multimodal frequency distribution and by the maximum 

and minimum values of individual components given by Zavarin and others (1989), at 

least three components seemed to be controlled by genes: α-pinene, 3-carene, and 

sabinene. Again, larger plots would help gain a better understanding of local variation. 

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

Figure 3-14—Distribution of P. monophylla and P. edulis (taken from Critchfield 

and Little 1966); (A) is location of P. edulis 

in California. 

Table 3-20—Average xylem monoterpene composition of six stands of P. edulis selected from 18 stands reported by Zavarin and 

others (1989), and the maximum and minimum values of the more variable components; N = number of trees 

Stand Locality 

No. county/state Monoterpene 1

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

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

9 Navajo, AZ 3 80.8 5.3 2.3 5.1 0.2 1.1 2.5 0.5 * 0.2 0.1 1.2 

14 Chafee, CO 10 75.9 0.8 0.8 6.1 0.3 1.2 5.2 0.3 5.7 0.1 2.7 1.0 

20 Coconino, AZ 10 80.7 3.8 1.5 5.2 0.8 1.0 2.6 0.4 0.3 0.2 0.7 2.2 

22 Culberson, TX 10 89.0 0.9 0.7 4.0 0.1 0.3 0.9 0.2 1.7 0.1 0.3 2.4 

34 Grant, NM 10 69.8 1.0 1.2 6.3 12.2 1.9 1.0 0.4 0.4 0.1 3.4 1.6 

38 Apache, AZ 10 65.5 0.9 0.7 17.3 0.2 3.0 2.6 0.8 1.6 1.5 5.2 0.8 

χ3 (188) 80.5 1.5 1.0 6.8 1.7 1.3 2.3 0.5 0.9 0.3 1.7 1.4 

Min 4 30 0 0 20 0 

Max 4 94 9 36 28 8 

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

p-cymene includes all trees reported by Zavarin and others. 2 Normalized; * = trace. 3 Averages for all trees; (188) includes all trees in Zavarin and others (1989). 4 As estimated from the frequency distributions of all trees given by Zavarin and others (1989). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 49 
Chapter 3 

19 Pine Species of California Smith 

In 1984, I sampled four trees growing at the Institute of Forest Genetics 

(IFG) from seed collected in southern New Mexico (table 3-21). The composition 

of three of the trees somewhat resembled that of trees reported from southern 

Arizona by Zavarin and others (1989), with about 65 percent α-pinene. 

However, the average of about 24 percent 3-carene reported in the trees at IFG 

was considerably higher than that reported by Zavarin and others (1989). The 

composition of the fourth tree was nearly pure α-pinene, a composition not 

reported by Zavarin and others (1989); from the frequency distribution such a 

composition probably occurs. Little or no difference in composition was found 

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

edulis pointed to the need for a larger number of trees at a location. 

#8. Pinus flexilis James (limber pine) 

P. flexilis is widely distributed in western United States, primarily in the central 

and northern Rocky Mountains (fig. 3-15), though it is also found on scattered 

ranges in the Great Basin. Its distribution is fairly limited in California and 

generally restricted to higher elevations. Mirov (1961) found the xylem monoterpene 

to be nearly pure α-pinene in trees in the White Mountains of California. 

I examined eight trees at the Institute of Forest Genetics (IFG) grown from 

seed collected from various locations. The composition varied so widely that 

the average composition was meaningless. Therefore, the composition of the 

individual trees was given (table 3-22). The sampling was far too small to make 

any reliable statements. However, α-pinene, ß-pinene, 3-carene, sabinene, and 

myrcene were quite variable and occurred in substantial amounts in some 

trees. Additionally, some trees had small to trace amounts of nonane, 

camphene, undecane, limonene, ß-phellandrene, ocimene, and terpinoline. The 

tree from Canada was sharply different from the trees from Idaho and Nevada. 

The Canadian tree was forked, and the composition of the two forks were 

nearly identical. The ratio of sabinene to terpinolene was about 3:1 in the seven 

trees that had measurable amounts of sabinene. This was a different ratio than 

that found in other pines reported in this chapter: P. muricata and P. albicaulis 

were about 1:1, P. monophylla was about 2:1. Little or no difference in monoterpene composition was found between a basal tree sample of P. flexilis 

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

It is apparent that a much more intensive and extensive sampling of P. flexilis 

would be helpful and is needed before more confident statements can be made. 

#9. Pinus jeffreyi Grev. and Balf. (Jeffrey pine) 

P. jeffreyi is primarily distributed in California, though its northern limits 

extend into southern Oregon and its southern limits into Baja California (fig. 3-

16). It is sometimes mistaken for P. ponderosa; commercially both are called 

western yellow pine. In the major portion of its range, P. jeffreyi generally 

grows at a higher elevation and on drier sites than P. ponderosa, though both 

species are found at the same elevation. Likewise, the elevational characteristics 

tend to be reversed in some places at the northern and southern limits of the 

range of P. jeffreyi. In northwestern California and southeastern Oregon, P. jeffreyi replaces P. ponderosa on abundant ultramaphic soils. Natural hybrids of P. jeffreyi and P. ponderosa, and of P. jeffreyi and P. coulteri, have been found, 

though more rarely than commonly believed. Cartwright (1988) sampled trees 

in six sympatric stands of P. jeffreyi and P. ponderosa and found that about 1 

percent were possible hybrids. P. jeffreyi was used in much of the pine 

hybridization studies at IFG from about 1940 to 1970. The compositions of some 

of the hybrids that were developed are given in Chapter 4. Mirov (1961) 

reported that all studies of the xylem resin showed that the volatile portion of 

P. jeffreyi was nearly pure heptane. 

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

Smith 19 Pine Species of California Chapter 3 

Table 3-21—Xylem monoterpene composition of individual trees of P. edulis growing at 

Institute of Forest Genetics (IFG) from seed collected in New Mexico; the remeasurements 

for trees No. 2 and 4 were made in 1988, 4 years after the first measurement 

Monoterpene 1 

Tree 

Number α-p cam ß-p car myr lim ß-ph oci terp 

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

1 96.0 0.5 0.8 - 0.5 

2 64.3 0.3 0.6 23.5 4.1 

3 58.1 0.3 0.5 29.6 2.1 

4 69.0 0.5 0.6 20.6 1.4 

2 65.0 0.2 0.6 23.0 4.2 

4 68.3 0.3 0.6 21.4 2.3 

1 α-pinene, camphene, ß-pinene, 3-carene, myrcene, 

- - 1.2 0.1 

0.6 - 3.4 3.1 

3.0 0.4 2.3 3.7 

0.3 - 3.4 4.1 

* 0.2 3.1 3.6 

* 0.2 4.0 2.9 

limonene, ß-phellendrene, 

ocimene, terpinolene. 2

 Normalized, *=trace, - =zero. 

Figure 3-15—Distribution of P. flexilis 

and P. storbiformis; A & B are possible 

introgression (taken from Critchfield 

and Little 1966). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 51 
Chapter 3 19 Pine Species of California Smith 

Table 3-22—Xylem monoterpene composition of eight P. flexilis, growing at the Institute of Forest Genetics from seed collected at 

the source 

Monoterpene 1 

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

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

Idaho 1.5 46.7 1.7 - 35.2 - 6.6 3.0 0.4 1.4 - 3.3 

Idaho 0.1 64.7 0.4 - 17.3 - 5.5 7.6 * 0.9 1.0 2.5 

Nevada * 67.4 3.4 - 17.8 - 8.2 1.2 1.0 - - 0.7 

Nevada 1.0 58.5 0.9 - 14.0 - 16.1 2.3 0.2 1.0 0.1 5.8 

Nevada * 54.7 0.7 - 13.5 - 19.8 1.8 * 1.5 0.1 7.9 

Canada 3

 0.1 30.0 0.1 - 7.4 48.1 * 10.7 * 0.7 0.2 2.8 

Canada 3

 0.1 29.7 0.1 - 7.2 47.8 * 11.2 * 0.7 0.2 3.0 

Nevada * 79.3 1.6 - 11.2 - 4.5 1.2 0.5 0.4 .2 1.0 

Nevada 1.5 71.0 1.3 - 10.3 - 8.1 2.0 0.8 0.8 - 4.0 

1

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

2

 Normalized; * = trace, - = zero. 

3

 These two measurements are forks of the same tree from Canada. 

Figure 3-16—Distribution of P. 

jeffreyi (taken from Critchfield 

and Little 1966), with location of 

six stands that were sampled. 

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

th 19 Pine Species of California Chapter 3 

An analysis was made of the volatile portion of the xylem resin of 128 trees 

growing at IFG from seed collected throughout the range of P. jeffreyi and from 

localities nearby on the Eldorado National Forest (Smith 1967b). The results 

(table 3-23) agreed, in general, with Mirov's report in that about 95 percent of 

the volatile portion was heptane with trace to small amounts of several 

monoterpenes. There were little or no differences in composition between a 

basal sample and one at 20 feet (see table 8-1). In addition to the 95 percent 

heptane, the three monoterpenes that occurred in the greatest amounts, but 

always less than 5 percent, were 3-carene, myrcene, and ß-phellandrene. A 

stand of 20 P. jeffreyi that was growing in the South Warner Mountains was 

analyzed for the volatile portion of the xylem resin. Again, the results were 

similar to those in previous reports except that one tree had characteristics 

suggestive of a hybrid with P. washoensis and/or P. ponderosa; its composition 

was 17 percent heptane, 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. The heptane and nonane showed P. jeffreyi parentage; 

the low α-pinene, high 3-carene, and trace of α-thujene suggested P. washoensis 

parentage; and the relative high limonene suggested P. ponderosa as a possible parent. Since all three parent trees grow fairly close together in this area, it is 

conceivable that all three species could be involved in the parentage. 

I sampled five stands to more thoroughly represent the range of P. jeffreyi 

pine (fig. 3-16). The size of stands varied greatly. 

The results again supported all the earlier reports: heptane was about 95 

percent of the volatile portion of the xylem resin with trace to small amounts of 

several monoterpenes (table 3-24); about 8 percent 3-carene was found in one 

tree and 12 percent ß-phellandrene in another. The frequency distribution of 

heptane, 3-carene, myrcene, and ß-phellandrene showed some variation. There 

tended to be a greater percentage of heptane and a lower amount of the minor 

components in the northern stands; the amount of heptane was also less variable 

in the northern stands (fig. 3-17). The data were not applicable to the coding 

procedure and only a selection of individual trees is given to show the range of 

composition (table 3-25). 

I concluded that P. jeffreyi had a (1-1) set of alleles for heptane, and there 

appeared to be no active alleles for any monoterpenes. The presence of trace to 

small amounts of several monoterpenes could have been caused by biosynthetic 

by-products or by environmental effects. However, the source of the biosynthetic by-products was not known because there were only very small 

amounts of the monoterpenes, and it was not likely that they would be derived 

from heptane. 

As discussed elsewhere, it could be that P. jeffreyi does have a (0-0) set of 

alleles for the monoterpenes and that these (0-0) sets can be slightly active. 

#10. Pinus lambertiana Dougl. (sugar pine) 

P. lambertiana is the largest of the pines in size, sometimes reaching a diameter 

of 10 feet, with diameters of 6 feet quite common in over mature stands. It 

usually occurs as a component of the mixed conifer forest and is not often found 

in pure stands. Though its principal range is in California, it extends 

northward into southern Oregon and southward into northern Baja 

California (fig. 3-18). P. lambertiana reaches its maximum growth in the 

central Sierra Nevada. 

Mirov (1961) reported a composition of 60 to 75 percent α-pinene, 5-10 

percent ß-pinene, and smaller amounts of ß-phellandrene and other 

monoterpenes. 

I sampled six stands, two in southern California and four in the Sierra 

Nevada/Cascades (fig. 3-18) with the standard macro-tap (see Chapter 2). The 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 53 
----------------------------------------------

Chapter 3 19 Pine Species of California Smith 

Table 3-23—Average composition of the xylem volatiles of 128 P. jeffreyi and a selection of individual tree composition (taken from 

Smith 1967b) 

Monoterpene 1 

Source N hep non α-p und cam ß-p car sab myr lim ß-ph ter 

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

2

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

Mean 128 94.7 1.1 0.4 0.5 * 0.2 1.4 * 0.9 * 0.8 * 

Eld 3 1 99.1 0.5 0.1 0.1 0 0.1 0.2 * 0 0 0 0 

Eld 1 94.6 3.0 0.5 0.2 0 0 0.2 0 0 0 1.4 0 

Eld 1 92.9 1.3 0.1 0.1 0 0.1 5.2 * 0.1 0 0 0 

Eld 1 90.7 1.3 0.4 1.0 0 0 3.6 * 1.6 0 1.5 0 

Mex 4 1 88.6 0.6 1.1 0.4 0 1.1 1.1 * 1.6 0.8 4.5 0 

Mex 1 90.1 1.2 1.6 1.1 0 1.7 1.8 * 0.4 0.6 1.6 0 

Eld 1 89.1 1.0 0.7 0.1 0 0.3 3.0 0.2 2.3 0.2 3.4 * 

1

 Heptane, nonane, α-pinene, undecane, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, terpinolene. 

2

 Normalized; * = trace. 

3

 Eld = trees growing on the Eldorado National Forest 

4

 Mex = trees growing at IFG from seed collected in Mexico. 

a

Table 3-24—Average composition of the xylem resin volatiles in five stands of P. jeffreyi; and the 

verage of all trees; n = number of trees 

Monoterpene 2 

Source n hep non α-p ß-p car myr lim ß-ph 

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

SB 66 94.7 0 0.3 0.7 0.1 0.8 0.2 2.5 

TH 16 91.6 0.9 0.4 0.4 1.5 1.6 0.1 3.0 

IN 36 95.3 0.2 0.4 0.2 0.4 0.4 0.1 2.3 

MR 40 93.5 0.6 0.6 0.1 0.6 1.5 0.1 1.3 

LA 103 98.0 0 0.3 0.5 0.1 0.5 0.1 0.1 

(261) 95.7 0.2 0.4 0.5 0.2 0.8 0.1 1.4 

1

 San Bernardino, Tehachapi, Inyo, Mt. Rose, Lassen. 2

 Heptane, nonane, α-pinene, ß-pinene, 3-carene, myrcene, limonene, ß-phellandrene. 3

 Normalized. 

= average ( ) = total 

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

Figure 3-17—Frequency distribution of 

the amount of the noted volatile components of the five stands of P. jeffreyi listed 

on t

s each 

represents n trees; ▲ is average of the 

indicate

he right; each dot is measurement of 

one tree except where 

set. 

(fig. 3-17 continues on the next 5 pages). 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 55 
Chapter 3 19 Pine Species of California Smith

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

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Chapter 3 19 Pine Species of California Smith

58 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 59 
Chapter 3 19 Pine Species of California Smith 

Table 3-25—Composition of xylem resin volatiles of selected P. jeffreyi illustrating variation in 

composition 

Monoterpene1 

Source2 hep non α-p cam ß-p car myr urn ß-ph 

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

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

MR 94.6 3.0 0.5 0 0.1 0.2 0 0 1.5 

MR 99.1 0.5 0.1 0 0.1 0.2 0 0 0 

SB 90.3 1.8 0.9 2.8 0 0.3 0.5 0 3.4 

SB 87.0 0.7 0.9 1.5 0 0 4.9 0 4.8 

SB 87.5 1.3 0.3 3.2 0 3.5 0 0.3 3.2 

SB 85.1 1.0 1.3 3.2 0 0.2 2.4 0 6.6 

TH 84.8 * 0.5 1.1 0 3.4 1.9 2.9 5.3 

TH 88.4 * 0.5 1.6 0 5.1 0.9 0 3.2 

TH 84.3 * 0.9 0.4 0 2.0 0.5 0.1 11.7 

TH 84.0 * 0.6 1.4 0.4 5.6 0.8 0.4 6.8 

IN 85.3 0.2 1.6 0.2 1.2 1.0 0.7 * 9.9 

MR 90.3 1.4 0.4 0.2 2.8 2.1 0.4 0 2.5 

MR 87.7 0.1 2.0 0.1 0.1 8.2 0.2 0.1 0.3 

1

 Heptane, nonane, α-pinene, camphene, ß-pinene, 3-carene, myrcene, limonene, ß-phellandrene. 2

 MR = Mt. Rose, SB = San Bernardino, TH = Tehachapi, IN = Inyo. 3

 Normalized; * = trace 

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

Figure 3-18—Distribution of P. lambertiana, taken from Critchfield and Little 

(1966), and the National Forest location 

of the six stands that were sampled for 

xylem monoterpene. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 61 
Chapter 3 19 Pine Species of California Smith 

average composition values of the trees recorded for each location (table 3-26) 

were misleading because of the great variation as shown by the ranges and by 

the frequency distributions (fig. 3-19). It is quite clear from these averages and 

the frequency distributions that the two southern California stands were quite 

distinct from the Sierra Nevada/Cascade stands in having an average of about 

10 percent undecane. The two southern California stands differed from each 

other in α-pinene, ß-pinene, 3-carene, myrcene, and limonene. The 11.6 percent 

myrcene in the San Bernardino stand was quite misleading because of the three 

trees with greater than 45 percent myrcene. Without these three trees, its frequency 

distribution was not at all different from the other stands. There was little or no 

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

The monoterpene α-pinene was extremely variable in all stands; even the 

few trees in the southern California plots showed great variation. Proceeding 

southward from the Deschutes, the average amount of α-pinene decreased 

through the Shasta and Lassen stands. However, the Eldorado stand went the 

other way, with the average increasing. The Los Padres stand had the lowest 

average, whereas the San Bernardino stand was about as low as the lowest of 

the four northern stands. 

Undecane was markedly different in the six stands; it was found in 

appreciable amounts in all trees in the Los Padres and San Bernardino stands, 

whereas it was absent from most trees in the four northern stands. When it did 

occur in the north, it was usually in small to trace amounts. 

Camphene was lacking in most trees in all stands; it was present only in 

small to trace amounts when it was found. 

ß-Pinene, like α-pinene, was quite variable in all stands. However, the 

average amount in the four northern stands was about the same. The 

average amount in the Los Padres stand was significantly lower than that 

in all other stands. 

3-Carene averaged about the same in the four northern stands except for 

the unusually large 22 percent in the Lassen stand; the San Bernardino stand 

was a bit lower, whereas the Los Padres stand was significantly lower. 

The ratio of 3-carene to terpinolene was in the range of 10:1 to 20:1, much 

like other pines. 

Sabinene was absent from most trees but occurred in small amounts in 

some trees and in appreciable amounts of up to 20 percent in a few trees in the 

Lassen, Eldorado, and Southern California stands. The ratio of sabinene to 

terpinolene was in the range of 3:1 to 4:1 which is much like the ratio in P. 

flexilis. Both P. lambertiana and P. flexilis are in the strobi subsection of the 

subgenus Strobes. Thus, this ratio could be a marker for the subsection. The 

ratio of sabinene to terpinolene in P. muricata and P. albicaulis is about 1 to 1, 

and in P. monophylla is about 2 to 1; these three species are in different 

subsections, and none is in the strobi subsection of the genus Pinus. The varying 

ratio of sabinene to terpinolene is puzzling, since where as, the ratio of 3-carene 

to terpinolene was always about the same, at about 20 to 1 in all pines. 

Myrcene averaged about the same in all stands; the higher average in the 

San Bernardino was caused by the three trees with greater than 45 percent. 

Limonene averaged about the same in all stands. The higher average in the 

San Bernardino stand was caused by three trees with greater than 45 percent 

limonene content. 

Beta-phellandrene averaged about 1 to 2 percent in all stands except in the 

Lassen where the average was slightly more than 3 percent. This greater 

average was caused by a general increase to about 6 percent in many trees and 

by the occurrence of several trees with greater than 9 percent. 

Terpinolene, as in all pines analyzed so far, followed the previously 

described pattern of 3-carene. 

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

Table 3-26—Average xylem monoterpene composition of stands of P. lambertiana in six national forests; n = number of trees 

Monoterpene 2 

National 

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

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

Des 68 56.8 0.2 0.1 19.8 9.5 0.1 6.7 4.9 0.8 1.1 

Sha 70 45.0 - 0.2 27.6 9.4 0.5 8.8 6.3 1.0 1.2 

Las 108 31.8 1.0 0.2 21.8 22.1 2.3 9.1 6.1 3.1 2.2 

Eld 109 51.4 1.3 0.1 25.2 8.1 2.5 6.3 1.1 2.2 1.4 

L. P. 18 22.3 7.7 - 7.8 46.1 0.4 7.6 3.2 0.7 4.2 

S.B. 31 34.1 10.7 0.2 19.4 12.8 0.5 11.6 8.9 0.8 0.9 

1

 Deschutes, Shasta-Trinity, Lassen, Eldorado, Los Padres, San Bernardino. 2 α-pinene, undecane, camphene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, terpinolene. 3

 Normalized; - = zero. 

Figure 3-19—Frequency distribution 

of the amount of the noted monoterpenes found in the xylem resin of stands 

of P. lambertiana, in the six National 

Forests listed on the right; each dot is 

indicates each represents n trees; 

measurement of one tree except where 

. 

▲ is average of set. 

(fig. 3-19 continues on the next 7 pages). 

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Chapter 3 19 Pine Species of California Smith

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th 19 Pine Species of California Chapter 3 

The frequency distributions of the individual components (fig. 3-19) showed 

the great variation within and between stands in nearly all components. There 

was reasonable evidence in the frequency data that five monoterpenes (α­

pinene, ß-pinene, 3-carene, myrcene, limonene) were under gene control and 

that all five frequency distributions were multimodal. The classification of 

sabinene was uncertain. It sometimes was found in amounts suggestive of gene 

control, but it was nearly absent in most trees. When the frequency distributions 

were viewed as a whole for the four northern stands, it was possible to define 

three modes each for α-pinene, ß-pinene, 3-carene, myrcene, and limonene 

(table 3-27). The two small stands in southern California were not considered in 

the determination of modes because they were too small and have unusually 

large amounts of undecane. 

When the coding procedure—using the criteria in table 3-27—was applied 

to the four northern stands (Deschutes, Shasta, Lassen, Eldorado), 65 types of 

composition were defined (table 3-28). Though sabinene occurred in the 5 to 15 

percent range in several trees and greater than 20 percent in a few trees, it could 

not meet the coding criteria and was not included in the coding process. These 

65 types of composition were very unevenly distributed among the four large 

northern stands (fig. 3-20). When the coefficient of association procedure was 

applied to the frequency of tree types in each stand, the results (table 3-29) 

clearly showed that the four northern stands were very poorly associated with 

each other. For example, the Deschutes stand had a large proportion of its 

composition types between types #55 and #65, whereas the other three stands 

had few or none of this type. The Shasta stand had a large proportion of its 

types between #37 and #45, the Lassen a large portion between #5 and #15, 

whereas the Eldorado had no grouping like the other three stands. 

Ten trees were selected from the Los Padres and San Bernardino stands to 

illustrate some of the more common types of composition (table 3-30). 

The grand mean for the 345 trees in the four northern stands was calculated 

(table 3-28). This was coded to 11011 type which was the fifth most common 

type of composition. Thus, the average for the species was the fifth most 

common type of composition. This illustrates the advisability of describing a 

stand, when variation is great, by the frequency of composition types and not 

by average composition. 

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

locally and regionally quite variable in the Sierra Nevada/Cascade stands. Five 

monoterpenes—α-pinene, ß-pinene, 3-carene, myrcene, and limonene—were 

quite variable and appear to be under gene control. Sabinene did not generally 

occur in amounts that were indicative of gene control except in a few trees in 

the Eldorado and Lassen stands. All four northern stands—Deschutes, Shasta, 

Lassen and Eldorado—had large within-stand variations and all four were 

very weakly associated with each other on the basis of the frequency of 

composition types. The Los Padres and San Bernardino stands were quite 

different from the four northern ones, primarily because of the presence of 8 percent to 10 percent undecane. The San Bernardino stand differed from the 

Los Padres stand by having larger amounts of limonene and myrcene. A stand 

of 100 trees may not be adequate in determining the range and frequency of 

types of composition; and larger stands are needed in Southern California. 

#11. Pi nus monophylla Torr. & Frem. (single leaf pinyon)

Pinyon pines are the typical conifer in the arid southwestern United States at 

lower elevations. Two species, Pinus monophylla and P. edulis, are by far the 

most common, occupying about 75,000 square miles (Lanner 1981). P. 

monophylla is generally found west of the Nevada-Utah state line, and P. edulis 

is found to the east of that line (fig. 3-21). Two other pinyons, P. discolor and 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 71 
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Chapter 3 19 Pine Species of California Smith 

Table 3-27—Intervals of the percentages of the frequency distribution of individual 

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

modes for the five noted monoterpenes 

Monoterpene 

Mode1 α-pinene ß-pinene 3-carene myrcene limonene 

---------------------------------- Intervals in percent 

0 0 - 30 0 - 20 0 - 15 0 - 2 0 - 2 

1 31 - 63 21 - 40 16 - 34 3 - 9 3 - 2 

2 64 - 100 41 - 100 35 - 100 10 - 100 13 - 100 

1

These mode numbers were used in the coding procedure in table 3-28. 

Figure 3-20—Distribution of the 65 

types of xylem monoterpene composition in the four northern stands of P. lambertiana; distribution is normalized for 

each stand; see table 3-28 for data on 

types of composition. 

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

Table 3-28—The 65 coded types of xylem monoterpene composition of P. lambertiana, their numerical 

abundance (N) within the 345 trees in the four northern stands, and their actual average monoterpene 

composition 

N 

Actual monoterpene composition1 

Code 

type 2 α-p und cam ß-p car sab myr lim ß-ph ter

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

1 00 021 25.8 0.2 0.4 15.9 11.3 26.5 8.6 3.0 6.7 4.0 

1 00 022 26.3 0 0 17.9 0 0 14.2 38.1 3.0 0 

1 00 110 26.2 1.6 0 19.3 23.2 15.3 4.9 0 4.2 5.0 

1 00 120 24.9 0 0.2 17.8 32.4 5.1 15.3 0 0.8 3.4 

2 00 111 17.2 1.5 0.7 10.0 27.7 12.8 7.8 11.4 9.0 2.1 

3 00 112 18.7 1.9 0.1 8.1 26.8 11.5 4.7 17.5 4.6 5.9 

3 00 121 18.6 0.9 0.2 15.5 28.5 5.7 13.9 6.5 5.8 4.1 

20 00 210 19.5 1.1 0.2 10.1 50.0 4.7 6.1 0.6 2.3 5.2 

12 00 211 18.0 0.3 0.2 6.0 54.0 1.8 6.5 5.4 1.3 6.1 

3 00 212 17.5 0.9 0 3.0 51.9 0 4.9 16.0 0.7 5.1 

9 00 220 20.0 0.7 * 12.2 46.1 1.1 12.4 0.2 1.4 4.8 

4 00 221 15.3 0.7 0.1 5.7 53.0 0 11.7 5.2 2.5 5.3 

2 01 012 23.5 2.0 0 26.8 0 0 6.2 32.7 8.9 0 

1 01 020 27.1 2.5 0.9 33.8 0 0 31.6 0 2.7 0 

2 01 022 24.9 0.8 0.2 29.9 0 0 13.2 29.3 1.9 0 

2 01 110 26.1 0.8 0 35.5 26.4 0 4.2 1.3 3.2 2.5 

6 01 120 22.3 0 0.1 28.0 30.0 0.3 14.7 0.3 2.7 1.6 

2 01 210 18.2 0.9 0.4 26.2 37.9 0 8.5 0.7 4.2 3.1 

1 01 211 25.8 0 0 24.6 38.5 0 4.5 2.5 0.6 3.3 

1 01 220 19.0 0 0.4 22.3 40.3 0 15.1 0 1.5 1.2 

1 02 020 31.0 1.3 0 45.3 0 0 18.8 0 1.5 0 

1 02 021 30.0 2.2 0 44.4 0 0 12.2 8.0 1.3 0 

1 10 011 60.7 0 0 20.2 0 0 7.2 11.0 0 0.9 

5 10 012 43.6 0.1 0.1 13.5 4.0 0.2 7.1 30.2 0.6 0.5 

4 10 020 56.9 0.8 0 18.6 0 0 20.9 0.1 2.3 0 

3 10 022 47.0 0 0.3 13.0 0 0 17.8 21.5 0.3 * 

6 10 100 49.0 1.6 * 10.4 24.3 7.2 1.8 0.2 0.8 4.5 

1 10 101 44.5 0 0.3 9.3 22.9 7.1 1.3 8.2 5.2 1.0 

21 10 110 41.6 1.5 0.1 10.9 23.5 9.2 5.3 0.5 2.3 4.5 

2 10 111 39.1 1.5 0.5 16.8 27.2 0 7.1 3.3 3.0 2.8 

2 10 112 35.2 0.3 0.1 10.0 19.3 3.6 4.8 23.3 0 3.5 

5 10 120 38.5 1.5 * 14.2 25.1 3.7 11.2 0.7 0.8 3.7 

3 10 121 38.5 0.1 0.3 15.3 18.3 7.9 11.2 1.0 3.4 3.5 

6 10 210 35.5 1.5 0.8 11.7 40.7 0 5.3 0.7 1.0 2.8 

(continues on next page) 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 73 
Chapter 3 19 Pine Species of California Smith 

Actual monoterpene composition 1 

Code 

N type 2 α-p und cam ß-p car sab myr lim ß-ph ter 

-----------------------------------------------------percent3

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

5 10 211 34.2 1.4 0.2 5.9 41.8 1.1 3.7 6.3 0.9 4.5 

1 10 220 32.7 1.3 0 11.7 35.5 0 10.8 0.7 3.0 4.1 

9 11 000 57.4 1.5 0.1 34.3 1.1 0.6 1.5 0.4 2.7 0.7 

2 11 001 55.4 0 0.3 38.1 0 0 1.8 2.7 1.6 0.1 

23 11 010 56.9 0.7 * 33.4 0.2 0 5.1 0.6 2.7 * 

16 11 011 56.4 0.1 0.1 29.7 1.8 0.2 4.3 5.7 1.2 0.1 

12 11 012 46.5 0.6 0.2 27.8 0 0.3 6.7 15.8 1.9 0.1 

22 11 020 49.3 0.8 0.2 32.4 0 0.7 13.8 0.3 1.9 0.3 

12 11 021 51.5 0.1 0.1 29.0 0 0.4 11.6 5.8 0.9 0.2 

6 11 022 37.9 0.9 0.2 27.9 0 0 12.3 18.8 2.0 0.1 

2 11 110 40.1 2.6 0.3 28.8 19.6 0 5.6 0.4 2.1 0.5 

1 11 121 36.7 0 0.2 25.3 20.6 0 10.8 4.9 0.9 0.7 

5 12 000 45.9 1.7 0 46.4 0 0 1.4 0.4 4.3 0 

17 12 010 41.3 1.1 0 47.7 0.1 0 6.3 0.2 3.2 0.1 

6 12 011 43.0 0 0.2 43.6 0.3 0 7.0 3.7 2.1 0.2 

12 12 020 39.1 0.1 0.1 44.6 0.2 0 13.1 0.4 2.7 0 

3 12 021 34.5 0 0.2 43.8 0 0 14.2 4.5 2.5 * 

1 12 022 31.1 0 0 41.7 0 0 11.6 13.6 2.0 0 

2 20 000 80.4 2.2 0.2 14.3 0.8 0 1.6 0 0.7 0 

2 20 001 74.1 0.8 0.1 15.7 0 0 2.0 6.5 0.7 0.1 

8 20 010 76.9 0.7 0 13.8 0 0 6.5 0.4 1.5 0.1 

8 20 011 72.3 0.1 0.2 16.4 0 0 4.3 6.0 0.6 0.1 

3 20 012 66.4 0.6 0 15.6 0 0 5.5 11.7 0 0.1 

4 20 020 72.2 0.1 0.2 14.8 0 0 12.0 0 0.8 0 

7 20 021 67.4 0.1 0.2 13.6 0 0 11.8 6.2 0.6 0.1 

1 20 022 63.3 0 0.4 11.3 0 0 9.6 15.2 0 0 3 

1 20 100 69.5 0 0.5 9.8 17.6 0 1.3 0.4 0.3 0.6 

5 21 000 68.5 0.5 0 26.5 0 0 1.0 0.1 3.2 0 

7 21 010 66.8 0.6 0.1 25.9 0 0 5.5 0.2 1.1 0 

11 21 011 62.9 0.6 0.1 22.2 4.1 0 4.2 4.8 0.7 0.4 

4 21 020 62.6 0 0.1 21.2 5.0 0 9.6 0.2 1.1 0.5 

345 [11011] 45.2 0.7 0.1 23.6 12.9 1.6 7.7 4.4 2.0 1.6 

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

terpinolene. 

2 From left to right α -pinene, ß -pinene, 3-carene, myrcene, limonene; see table 3-27 for values of coded numbers. 

3 Normalized; * = trace. 

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

Table 3-29—Coefficients of association of the four northern stands of P. lambertiana 

National 

Forest Eld Las Sha Des 

-------------------------------------coefficients--------------------------------------

Eldorado .10 .01 .06 

Lassen .02 .04 

Shasta .03 

Deschutes 

Table 3-30—Xylene monoterpene composition of 10 individual P. lambertiana, selected from a population of 49 trees, which illustrate the range 

in composition in the Los Padres and San Bernardino stands 

Monoterpene 1 

Stand α-p und ß-p car sab myr lim ß-ph ter 

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

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

Las Padres 3.8 8.5 3.4 73.3 * 4.0 * 0.6 6.1 

22.4 6.1 6.3 51.9 * 7.4 * 0.7 4.8 

3.1 8.4 1.5 43.0 - 3.2 40.0 * 1.0 

36.3 4.7 39.1 - - 17.5 - 2.3 -

7.2 16.9 5.7 53.2 0.5 11.5 * 0.7 4.6 

San Bernardino 37.3 8.6 2.3 - - 51.3 - - -

64.6 12.6 16.0 - - 2.9 0.7 1.6 1.6 

33.6 10.2 - - - 9.2 46.6 - -

4.1 14.0 1.2 - - 7.1 73.3 - -

48.6 2.8 23.3 - 13.4 6.5 0.5 - 4.3 

1 α-pinene, undecane, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene, terpinolene. 

2 Normalized; * = trace, - = zero. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 75 
Chapter 3 

19 Pine Species of California Smith 

(formerly, P. cembroides) and P. quadrifolia, are primarily found in Mexico, but 

their ranges just reach into the adjoining States of Texas, New Mexico, Arizona, 

and California. 

In early work, Mirov (1961) reported that P. monophylla and P. edulis had 

quite similar monoterpene composition, i.e., a large percentage of α-pinene and 

much smaller amounts of several other monoterpenes. Zavarin and others 

(1971) examined the two species more closely using gas chromatography and 

concluded that the composition of the two species was too similar to be a strong 

diagnostic character for determining species of individual trees. They did find, 

however, some average differences between the two species, with limonene 

higher in P. monophylla and 3-carene higher in P. edulis. Zavarin and others 

(1971) also found some evidence of geographic differences in P. monophylla and 

showed some variation in some of the components. Zavarin and Snajberk 

(1980) extracted resin from the xylem of 11 species of pinyon and found large 

differences between some species, but, again, only small differences were 

found between P. edulis and P. monophylla. A study was subsequently made of 

P. monophylla and P. quadrifolia where their ranges overlap in southern 

California (Zavarin and others 1980). Both species were high in α-pinene; stand 

averages for 10 trees for P. quadrifolia ranged from 93 to 95 percent, and for P. 

monophylla ranged from 77 to 86 percent. P. monophylla had greater amounts of 

camphene, myrcene, and limonene than P. quadrifolia. 

I sampled five stands that represented the trees' range (fig. 3-21, table 3-31). 

The results have been reported (Smith and Preisler 1988). Subsequent to that 

work I sampled a stand near Pine Mountain on the Los Padres National Forest. 

The following discussion was adapted from the two studies. 

The six stands fairly well represented the range of P. monophylla, though no 

stand was located near P. edulis, along the eastern limits of P. monophylla, and 

no stand was located near P. quadrifolia along its southern limits (fig. 3-21). 

A total of 10 monoterpenes were identified in the xylem resin of the 533 

trees of P. monophylla sampled (table 3-32). Three of these—ß-pinene, ßphellandrene, and camphene—occurred in trace amounts or less than 1 percent; 

two others—ocimene and terpinolene—comprised 1 to 8 percent of the total 

monoterpenes and have a unimodal distribution. The remaining five 

components—α-pinene, 3-carene, sabinene, myrcene, and limonene— 

ranged considerably in amounts and tended to have a trimodal distribution 

(fig. 3-22). Little or no difference in composition was found between a basal tree sample and one at 20 feet (see table 8-1). 

A comparison of the different studies of P. monophylla, as noted above, 

showed fairly similar average composition (table 3-33), but the larger sample 

had a much greater range for all major components. 

Among the six stands in the range-wide study, α-pinene averaged 84 to 85 

percent in the two Nevada stands, Austin and Ely, while averaging 76 to 80 

percent in the four California stands: Diamond Valley, Mammoth Lakes, Pine 

Mountain, and Wrightwood (table 3-32). 3-Carene averaged less than 1 percent 

in the Nevada stands while averaging 2 to 4 percent in the California stands. 

Sabinene averaged about 2 percent at Austin, Ely, and Diamond Valley; about 3 

to 4 percent at Wrightwood and Pine Mountain; and about 2 percent at 

Mammoth Lakes. Limonene averaged about 3 percent at Austin. Myrcene 

averaged about 5 to 6 percent in all stands. 

Measurements of 12 sets of forked trees with low forks, which were fairly 

common in single leaf pinyon, showed that the compositions of the two forks of 

a tree were almost identical; the compositions of the sets of forks were fairly 

representative of the stand. 

From the frequency distribution of α-pinene, 3-carene, sabinene, 

myrcene, and limonene in five of the stands (fig. 3-22), three levels of 

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

Figure 3-21—Distribution of P. 

monophylla, taken from Critchfield and 

Little (1966). 

Table 3-31—Locations of six stands that were sampled for the monoterpene composition of xylem resin 

in P. monophylla 

State Physiographic Trees 

locality and abbr. area National Forest sampled 

no. 

California 

Diamond Valley DV Carson Valley Toiyabe 96 

Mammoth Lake ML Owens Valley Inyo 91 

Wrightwood WW San Gabriel Mtns Angeles 99 

Pine Mountain PM Pine Mountain Los Padres 47 

Nevada 

Austin AU Toiyabe Range Humboldt 100 

Ely EL Ward Mountain Humboldt 100 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 77 
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Chapter 3 19 Pine Species of California Smith 

T able 3-32—A verage m o noterpene com posi tion of the xy lem resin in six stands of 

P. m o nophylla; see ta ble 3 -3 1 f o r location of stands; n = num ber of tr ees 

California Nevada 

Monoterpene DV 1 ML PM WW AU EL 

n=96 n=91 n=47 n=99 n=100 n=100 

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

α-Pinene 79.8 77.4 76.4 80.3 85.0 84.3 

Camphene * * * * * * 

ß-Pinene 0.4 0.4 0.7 0.4 0.0 0.0 

3-Carene 4.0 2.2 2.9 3.0 0.4 0.4 

Sabinene 2.1 5.8 4.9 3.1 1.8 2.1 

Myrcene 6.4 5.1 4.9 4.5 5.1 5.3 

Limonene 0.9 1.9 1.6 2.4 3.0 1.1 

ß-Phellandrene * * 0.2 * * * 

Ocimene 3.5 3.2 4.5 3.6 2.3 3.6 

Terpinolene 2.5 3.4 3.5 2.7 1.0 2.0 

1 Diamond Valley, Mammoth Lakes, Pine Mountain, Wrightwood, Austin, Ely. 2 Normalized; * = trace. 

Table 3-33—Comparison of the averages (x), and the ranges of the xylem monoterpenes of P. monophylla: from Zavarin and others (1971, 1980) and this report; n = number of trees sampled 

1971 1980 1995 

Monoterpene n = 14 n = 40 n = 533 

x range x1 x range 

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

α-Pinene 82.5 67 - 90.0 81.2 81.4 40 - 97 

Camphene 0.5 0 - 1.0 2.2 * * 

ß-Pinene 1.0 0 - 1.0 1.0 0.4 0 - 3 

3-Carene 0.5 0 - 4.0 0.7 2.1 0 - 47 

Sabinene 3.5 0 - 12.0 .0 3.0 0 - 24 

Myrcene 6.0 3 - 13.0 6.3 5.3 0 - 22 

Limonene 2.0 0 - 13.0 5.1 1.9 0 - 23 

ß-Phellandrene * 0.1 1.2 * * 

Terpinolene 2.0 0 - 7.0 1.0 2.3 0 - 11 

γ-Terpinene .0 .0 * .0 0 

Ocimene 2.0 1 - 4.0 0.6 3.2 0 - 10 

p-Cymene .0 .0 0.5 .0 0 

Total 100.0 99.8 99.6 

1 No ranges given in Zavarin and others (1980). 2 Normalized; * = trace 

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

Figure 3-22—Frequency distribution of 

the amount of the noted monoterpenes 

in six stands of P. monophylla, listed on 

the right; each dot is measurement of 

one tree, except for sabinene, 3-carene, 

and limonene where each large dot indicates four trees and each small dot indicates one tree; ▲ is average of stand. 

(fig. 3-22 continues on the next 4 pages). 

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th 19 Pine Species of California Chapter 3 

occurrence were given code values of 0, 1, 2, (table 3-34). In fig. 3-22, each dot is 

one tree for a-pinene and myrcene, but for sabinene, limonene, and 3-carene 

each large dot is four trees and each small dot is one tree. The monoterpene 

composition for each tree was then expressed as a five-digit value in terms of 

the code values for a-pinene, 3-carene, sabinene, myrcene, and limonene. A 

total of 41 tree types of composition were identified; 28 occurred more than 

once, and 13 occurred only once (table 3-35). The individual trees varied from 

type 20000 to type 01211. 

Five types of composition—20000, 10100, 20100, 10010, 10110—comprised 

about 70 percent of the trees (fig. 3-23). These five types were found in each of 

the five stands, but differed markedly in frequency. For example, type 20000 

accounted for about 49 percent of the trees at Austin but only about 13 percent 

of the trees at Mammoth Lakes. Type 10100 accounted for about 38 percent of 

the trees at Mammoth Lakes but only about 9 percent of the trees at Diamond 

Valley. The types that did not occur in all stands varied markedly in presence 

and frequency. For example, type 00200 represented about 6 percent of the 

trees at Mammoth Lakes but was not found in the other stands. 

The coefficient of association, based on the occurrence of types of 

composition, was calculated within and between stands; the within-stand 

calculation was based on a comparison of the first and second half of the stand 

in order of sampling. 

All coefficients of association within stands were about 0.90; coefficients 

between stands were considerably lower, suggesting that the five stands were 

different (fig. 3-24). The coefficients were strongest between the three northern 

stands, Diamond Valley, Ely, and Austin. Surprisingly, two of the most distant 

stands, Ely and Wrightwood, had a comparatively strong association of 0.45; 

and two of the closest stands, Diamond Valley and Mammoth Lakes, had a 

comparatively weak association of 0.12. Could the 0.90 coefficient of association 

between the two halves of the stands be a measure of inherent local variation? 

In some pine species, it is possible to determine the relation of 3-carene 

to terpinolene, and of sabinene to terpinolene as noted earlier for P. albicaulis 

and P. lambertiana. P. monophylla presented an opportunity to look at these two relations in the same species. There were 59 trees with only sabinene and 

terpinolene and nine trees with only 3-carene and terpinolene. There were 

many other trees with all three components; these could not be used for 

determining ratios. The results of the analysis of the ratios showed the ratio of 

3-carene to terpinolene was about 6:1, and the sabinene-to-terpinolene ratio 

was between 2:1 and 1:1 (fig. 3-25). Both ratios were different from other pines. 

The ratio of 3-carene to terpinolene found in most pines was about 20:1, the 

ratio of sabinene-to-terpinolene varied from about 1:1 to 3:1. 

The sampling of the species did not include areas where P. monophylla 

could hybridize with P. edulis in the east or with P. quadrifolia in the 

southwest. Lanner (1974) reported considerable morphological evidence of 

hybridization of P. monophylla with P. edulis where two species occur 

together in western Utah. Zavarin and others (1980) report on possible 

hybridization of P. monophylla with P. quadrifolia in southern California and 

Baja California. 

Zavarin and Snajberk (1980) also proposed three subspecies for P. 

monophylla as follows: 

1. Subsp. monophylla in the major portion of the range north and west of a 

line from Los Angeles County to about Lake Mead. 

2. Subsp. californium in the area south of the demarcation noted in (1). 

3. Subsp. fallax in the area of northeastern Arizona. 

The scope of the work reported in this volume did not permit comment on this 

subdivision of P. monophylla; all stands that were sampled were within the 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 83 
--------------------- 

Chapter 3 19 Pine Species of California Smith 

Table 3-34—Intervals that were used to define the low (0), medium (1), and high (2) 

modes in the frequency distribution of the individual monoterpenes of P. monophylla 

Code value 

0 1 2 

Monoterpene 

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

α-Pinene 0 - 70.4 70.5 - 84.4 84.5 - 100 

3-Carene 0 - 4.4 4.5 - 11.4 11.5 - 100 

Sabinene 0 - 2.4 2.5 - 10.4 10.5 - 100 

Myrcene 0 - 7.4 7.5 - 16.4 16.5 - 100 

Limonene 0 - 5.4 5.5 - 16.4 16.5 - 100 

Figure 3-23—Occurrence of 

monoterpene composition types 

in five stands of P. monophylla at 

Austin (AU), Ely (EL), Diamond 

Valley (DV), Wrightwood (WR), 

Mammoth Lakes (ML); see table 3-

35 for actual composition of 

coded types. 

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

Table 3-35—Twenty-eight coded tree1 types of composition found in P. monophylla, their actual composition, and their occurrence in the species; see figure 3-23 for occurrence of types in each stand. 

Composition Occurrence in 

Coded type2 Actual2, 3 the species4 

α 3 s m l α-p car sab myr lim O+T 

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

2 0 0 0 0 90.5 0.2 0.4 4.2 0.9 3.5 31.7 

1 0 1 0 0 80.3 0.4 5.7 4.7 0.9 7.4 21.4 

2 0 1 0 0 87.0 0.2 4.1 3.0 0.7 4.8 8.6 

1 0 0 1 0 81.4 0.5 0.5 11.0 1.3 5.0 6.2 

1 0 1 1 0 76.4 0.1 5.0 9.4 1.1 7.6 3.4 

2 0 0 1 0 86.3 0.1 0.4 8.7 0.6 2.6 3.1 

0 2 0 0 0 57.9 26.8 0.4 6.1 1.0 7.7 2.0 

1 0 0 0 0 81.7 1.3 0.9 5.6 1.3 8.6 1.8 

0 2 1 0 0 59.4 19.3 5.9 4.7 0.7 11.2 1.8 

1 0 0 0 2 73.0 0.2 0.4 2.3 20.0 2.9 1.4 

1 0 1 0 1 75.6 0.5 4.2 1.7 12.4 4.8 1.4 

1 2 0 0 0 75.2 15.5 0.3 3.5 1.9 4.2 1.4 

1 0 0 0 1 78.9 0.0 0.3 2.8 12.9 6.0 1.2 

1 1 0 1 0 76.5 7.7 0.0 9.3 1.0 5.1 1.2 

1 1 1 0 0 75.7 6.8 4.7 3.9 0.9 7.8 1.0 

0 0 1 0 1 66.1 0.6 7.5 3.0 13.0 8.2 1.0 

0 0 2 0 0 65.7 0.0 15.2 5.1 2.0 11.0 1.0 

0 0 2 1 0 60.4 0.4 14.7 11.9 1.0 11.2 1.0 

0 1 1 0 0 67.7 7.0 7.0 5.0 1.6 11.2 1.0 

1 1 0 0 0 81.5 8.5 0.6 1.9 1.8 4.7 0.8 

0 0 1 1 0 67.0 0.6 8.8 12.2 1.4 9.6 0.8 

2 1 0 0 0 87.3 5.9 0.0 3.4 0.3 3.0 0.6 

1 0 2 0 0 73.6 0.7 14.2 4.5 0.5 5.8 0.6 

0 2 0 1 0 66.8 19.6 0.0 9.2 0.7 5.0 0.6 

2 0 0 0 1 86.1 0.0 0.1 1.9 7.8 3.6 0.4 

1 0 0 2 0 75.9 1.1 0.0 17.1 1.5 3.6 0.4 

1 2 1 0 0 72.4 12.1 4.7 4.5 0.1 5.9 0.4 

0 2 1 1 0 59.2 15.2 7.1 9.4 0.7 7.5 0.4 

1 15 types (not tabled, occurred once: 10011, 10102, 10111, 10210, 11001, 00020, 01001, 01101, 01200, 02101, 

02210, 00100, 00120, 00010, 01211, 00100, 00120, 00010. 

2 α-pinene, 3-carene, sabinene, myrcene, limonene, ocimene + terpinolene. 

3

 Normalized for each coded type. 

4

 Normalized for all trees in all stands. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 85 
Chapter 3 19 Pine Species of California Smith 

Figure 3-24—Coefficient of association, r, 

indicated by numbers on lines, between 

stands of P. monophylla based on the occurrence of types of monoterpene composition; 

distribution of species was taken from 

Griffen and Critchfield (1972). AU = Austin, 

DV = Diamond Valley, EL= Ely, ML = 

Mammoth Lakes, WW =Wrightwood. 

Figure 3-25—Correlation of the 

amounts of 3-carene/terpinolene (○) and 

of sabinene/terpinolene (●) in the xylem 

resin of P. monophylla. 

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

region assigned to subsp. monophylla. Likewise, it appeared that the taxonomy 

and relationships of P. monophylla and P. edulis cannot be adequately resolved 

on the basis of xylem monoterpenes. There were only small differences between 

the means of the two widespread pinyons, P. monophylla and P. edulis, and there 

was considerable overlap in the maximum and minimum of the individual 

monoterpenes, at least as could be determined from the S.D. values of P. edulis 

reported by Zavarin and others (1980). 

Anderson and others (1970) found quite a different composition when 

extracting monoterpenes by steam distillation of mill-ground xylem: 46 percent 

α-pinene, 22 percent myrcene, 8 percent ß-phellandrene, 7 percent limonene, 1 

percent camphene, 2 percent ß-pinene, 5 percent γ-terpenene and 4 percent 

terpinolene. Reports on other pines using steam distillation of mill-ground 

xylem usually differed from the composition reported by GLC analysis of fresh 

resin. Apparently steam distillation of xylem changed the composition of the 

monoterpenes. However, there was no change in composition with steam 

distillation of fresh resin followed by vacuum separation by Mirov (1961) or by 

short-path distillation of fresh resin at atmospheric pressure (see Chapter 8). 

The genetic structure of α-pinene was likely the same in all P. monophylla 

reported in this chapter: a (1-1) set of additive alleles at a single locus and 

variation in composition were caused by differing alleles for 3-carene, 

sabinene, myrcene, and limonene. Thus the condition is much like that noted for 

ß-phellandrene in P. contorta earlier in this chapter. Though the average 

composition for 3-carene, sabinene, myrcene, and limonene was low (table 3-32), 

well below 6 percent, there were individual trees with a large enough amount to 

be considered of genetic origin, albeit a rare allele (table 3-35, fig. 3-22). 

#12. Pinus monticola Dougl. (western white pine) 

P. monticola is widely distributed in western North America, and its range can 

be viewed as two nearly disjunct sections. A Rocky Mountain section ranges 

from southeastern British Columbia southward to north central Idaho, 

northeastern Washington, and northwestern Montana with scattered stands in 

northeastern Oregon (fig. 3-26). A western section extends from southwestern 

British Columbia southward along the Cascades, Klamath Mountains, and the 

Sierra Nevada to central California. 

Mirov (1961) sampled trees from the Warner Mountains and determined 

that the xylem resin was composed of about 60 percent α-pinene, 26 percent ßpinene, and 2 percent undecane. He later sampled trees from Priest River in 

northern Idaho and found the following results: 2 percent heptane, 32 percent 

α-pinene, 45 percent ß-pinene, 7 percent limonene, 2 percent undecane, and 12 

percent others as well as sesquiterpenes. 

Hanover (1966) analyzed the cortex resin of 1- to 3-year-old tissue of older 

trees and compared the variability in α-pinene, ß-pinene, myrcene, 3-carene, 

and limonene. He found a considerable range in composition between trees 

and little variation within trees. 

Zavarin and others (1990) conducted an extensive sampling of the xylem 

monoterpenes of P. monticola in which they also found a large range in several 

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Chapter 3 19 Pine Species of California Smith

and the 

stands. 

Figure 3-26—Distribution of P. monticola, 

taken from Critchfield and Little (1966) 

location of the three sampled 

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

of the components. They sampled 20 stands of about 10 trees each in a fairly 

comprehensive sampling of the tree's range. 

I sampled three stands between 1983 and 1985 as follows (fig. 3-26): 

Stand National Number 

no. Forest Locality of trees 

1 Eldorado Echo Summit 104 

2 Shasta-Trinity Lake Siskiyou 60 

3 Deschutes Lookout Mountain 16 

The results showed that the three localities differed markedly in average 

composition (table 3-36) and that there was a great range in the frequency 

distribution of the individual components (fig. 3-27). Though α-pinene occurred 

most abundantly, a large number of trees had considerable amounts of 

undecane, ß-pinene, 3-carene, limonene, and ß-phellandrene. There were also 

some trees with moderate amounts of sabinene and camphene. The ratio of 

sabinene to terpinolene was about 2:1, thus much like P. lambertiana. The 

averages reported by Zavarin and others (1990) for 10-tree plots near the three 

stands reported here were somewhat similar, but a 10-tree stand appeared to be 

inadequate for describing the composition of a species with such great 

variability. When all three stands were viewed together, a trimodal distribution 

can be defined and coded for α-pinene, ß-pinene, 3-carene, myrcene, and 

limonene (table 3-37). Using the modal criteria in table 3-37, all trees were coded 

and the frequency of types of composition was determined (table 3-38). These 

showed a great range in composition types in the Eldorado stand, with a total 

of 38 types, Shasta had only seven types, and Deschutes nine types, though 

there were only 16 trees in the sample (fig. 3-28). 

Of the 38 types in Eldorado, 18 occurred only once. No type was abundant 

in all three stands. For example, there were 33 trees in aggregate in types 12000, 

12001, 12002, and 12011 in the Eldorado stand, while Shasta and Deschutes had 

only one tree with these same four types. Likewise, Shasta had 41 trees in 

aggregate in types 20000 and 20001, while Eldorado had only two. Two trees of 

the 10100 type had unusually large amounts of (3-phellandrene: one with 24.6 

percent and one with 23.4 percent. One of the trees in type 12000 had 18.4 

percent ß-phellandrene, and one tree in type 02000 had 21.5 percent. The 21000 

type was the only one that was fairly common in all three stands: 4 percent in 

Eldorado, 16 percent in Shasta, and 30 percent in Deschutes. 

The coefficient of association for the Eldorado and Shasta stands was 0.0. 

No determination was made for the Deschutes stand because it had only 16 

trees. 

A comparison of my study (reported above) and that of Zavarin and others 

(1990) cannot be made with confidence because the latter reported only average 

composition and did not give kinds of individual tree composition nor 

frequency distribution characteristics. However, it is readily apparent that 

there was a great range in the amount of α-pinene, ß-pinene, 3-carene, sabinene, 

myrcene, limonene, and ß-phellandrene. There was considerable similarity in 

the ranges of the individual components found by Zavarin and others (1990) in 

20 stands located throughout the tree's distribution, and in the ranges reported 

here (table 3-39) from three stands located in the southwest portion of the tree 

distribution. The evidence suggested the advisability of a more intensive and 

extensive study of the xylem monoterpenes of P. monticola. 

USDA Forest Service Gen. Tech. Rep. PSW-GTR-177. 2000 89