196b 

introduction, Spread 

and Areal Extent of 

Saltcedar (Tamarix) 

in the Western States 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 491-A 

Introduction, Spread 

and Areal Extent of 

Saltcedar (Tamarix) 

in the Western States 

By T. W. ROBINSON 

STUDIES OF EVAPOTRANSPIRATION 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 491-A 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1965 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 
CONTENTS 

·Abstract __________________________________________ _ 

Introduction ______________________________________ _ 

Entrance into the United States _________________ _ 

Time of general awareness of saltcedar in the Southwest _______________________________________ _ 

Occurrence, spread, and density of saltcedar growth ____ _ Areal extent ___________________________________ _ 

Page 

A1 

1 

3 

4 

6 

s 

Occurrence, spread, and density, etc.-Continued 

Water consumption ____________________________ _ 

Effect on stream regimen _______________________ _ 

Future considerations ________________ --- _______ ----_ References ________________________________________ _ 

.Page 

AS 

10 

10 

11 

ILLUSTRATIONS 

PLATE 1. Map showing occurrence of saltcedar in the 

western States ______________________ In pocket 

Page 

FIGURE 1. Dense saltcedar growth along the Gila River_ A2 

2. Increase in the area of saltcedar growth and 

cover density along the Pecos River in 

New Mexico___________________________ 7 

FIGURE 3. Aerial photographs, in 1936 and 1957, of the Page 

Arkansas River valley at the Otero-Bent 

County line, Colorado___________________ A9 

TABLES 

TABLE 1. Tamarix specimens collected in the Western 

States (1S77 to 1920)--------------------

Page 

A5 

Page 

2. Gross areas of saltcedar growth in the West- ern States as of 196L __________________ _ AS 

In 

STUDIES OF EVAPOTRANSPIRATION 

INTRODUCTION, SPREAD, AND AREAL EXTENT OF SALTCEDAR (TAMARIX) IN THE 

WESTERN STATES 

By T. W. RoBINsON 

ABSTRACT 

Saltcedar, the name generally applied to two exotic deciduous 

species of the genus Tamarix, was introduced into this country 

more than 100 years ago and has, in the last 30 years, become 

very much of a nuisance plant in the arid and semiarid regions 

of the Western States. The species are highly water-consuming, salt-tolerant, naturalizing shrubs that have escaped from 

cultivation and spread rapidly from one stream valley to 

another. 

Saltcedar occurs in 15 of the 17 Western States. Areas infested range from less than 1,000 acres each in Idaho, Montana, 

Nebraska, and South Dakota, to about 450,000 acres in Texas. 

Its dense growth along stream channels presents a barrier to 

flood flows, and thereby increases flood hazards and sediment 

deposition. The time of awareness of the plant by residents 

of the region was generally in the 1920's. 

The total area of saltcedar growth has increased from an 

estimated 10,000 acres in 1920 to more than 900,000 acres in 

1961. It is possible that by 1970 saltcedar will be growing on 

11;3 million acres. Not only is the growth increasing in areal 

extent but also in density of growth. The consumptive waste 

of ground water by the plant is estimated as 40 to 50 thousand 

acre-feet in 1920, 3.5 million acre-feet in 1961, and possibly 5.0 

million acre-feet by 1970. 

INTRODUCTION 

Since about 1930 saltcedar has become a nmsance 

plant in the arid and semiarid regions of Western 

States. In these regions saltcedar is the common name 

by which the deciduous species T. pendantra Pallas and 

T. gallica Linnaeus of the genus Tamarix are known. 

Saltcedar is a highly water-consuming naturalizing 

shrub that has escaped from cultivation and spread 

rapidly from one stream valley to another. An aggressive plant, it has not only invaded but has entirely 

replaced the native vegetation in many areas. The 

dense junglelike growth shown in figure 1 is typical of 

its occurrence in a well-established stand. Owing to 

the rapid spread of the plant, its high water consumption, and the potential flood hazard engendered by it, 

saltcedar is of concern to the residents of these regions. 

This concern becomes greater each year as the demand 

for water increases, the need for reducing flood hazards 

mounts, and, at the same time, the areal extent and 

growth density of the plants are increasing. 

The genus J'amam, introduced into the Western 

States from the Mediterranean area, is one of the four 

genera of the Tamaricaceae family native to Africa, 

Asia, and Europe. Although many species of the genus 

have been brought into this country, only two have 

escaped from cultivation to become important in the 

saltcedar problem. 

As a means of evaluating the magnitude of the problem posed by saltcedar, the Phreatophyte Subcommittee 

of the Pacific Southwest Inter-Agency Committee proposed an inventory of the areas of saltcedar growth. 

In 1958, the author began to assemble information on 

the location of areas of saltcedar growth. Although 

saltcedar was known to have spread widely since about 

1920 and to be growing on thousands of acres in the 

Western States, this report represents the first attempt 

to map its distribution and areal extent. A brief history 

also was prepared dealing with the time of introduction 

and subsequent spread of the plants. 

In addition to field mapping, information was collected from all available sources. These include published and unpublished reports, information from Federal and State agencies, and reports by county agents 

and consulting engineers and from interested individuals. The offices of the State Engineers of Utah and 

New Mexico and the Colorado Water Conservation 

Board provided a large amount of data on phreatophyte 

arowth in these States based on partial inventories made 

~nder their direction. In Texas most of the information was supplied by the Soil Conservation Service and 

was based on a general reconnaissance of saltcedar infestation. Vegetative surveys by the Bureau of Reclamation provided information concerning the Gila River, 

Ariz., and the Colorado River from Davis Dam to the 

international boundary. Field offices of the Water Resources Division, Geological Survey, located in the 

Western States, were very helpful in supplying data 

about their respective States. 

AI 
FIGURE 1.-Dense saltcedar growth along the Gila River, 40 miles east of Phoenix, Ariz., In the vicinity of Powers Butte, 1958. 

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SALTCEDAR LN THE VVESTERN STATES A3 

The species growing in this country may be divided 

into the evergreen and deciduous types. The evergreen 

type generally is represented by the athel tree T. aphylla 

Linnaeus. It has been planted extensively as an ornamental, a shade tree, and windbreak largely in the 

desert areas of the Southwest, but has rarely become 

naturalized. It is not a problem plant. Likewise, the 

deciduous T. tetrandra has been widely used as an ornamental shrub, but has nowhere become an aggressive 

plant. 

Originally thought to be confined to the warm and 

arid Southwest, saltcedar has spread northward since 

about 1950 into the Great Basin, the Roeky Mountains, 

and some of the Plains States. 

The two species of the deciduous type that have 

escaped cultivation are T. pentandra and T. gallica. T. 

pentandra grows profusely along river bottoms 

throughout the West, but T. gallica appears confined 

to salty soils near the Texas Gulf Coast. 

ENTRANCE INTO THE UNITED STATES 

Introduction of the species, which are native to the 

Old World from western Europe to the Himalaya Mountains, into the United States is not of firm record 

(Bowser, 1958). In discussing its introduction, Bowser 

notes (p. 13-14) that tamarisk could have been established in Mexico at an early date by Spanish explorers 

and conquistadors. Inasmuch as these invaders made 

expeditions into South-Central United States between 

1540 and 1750, it could have been established here also. 

If tamarisk had been established by the early Spanish 

explorers, Mexico would have been the center of distribution and it would have been found in abundance there. 

The sparsity of collection of tamarisk specimens from 

Mexico, however, does not support this assumption. In 

the National Herbarium of the Smithsonian Institute, 

Washington, D.C., there is only one collection of tamarisk from Mexico, and this from the border town of 

Nogales, while there are many from other Latin American countries such as Argentina, Venezuela, Chile, and 

Ecuador. Extensive collections of other plant species 

from Mexico, some very early, some modern, are filed in 

the Smithsonian Institute. 

What appears to be support for the assumption that 

the tamarisk was introduced into this country by the 

early Spanish explorers may be found in the journal 

of Father Escalante (Auerbach, 1943) . Father 

Escalante was one of the early Spanish padres who 

explored the United States as far north as Utah. According to the translation of his journal, Father 

Escalante reported tamarisk at Fort Pierce Wash near 

the Utah-Arizona border in 1776. Dr. E. L. Little, 

Jr., Forest Service dendrologist, points out (oral 

commun., 1963) that there is some question concerning 

the translation of the word "taray" which Father 

Escalante used to describe the plant he observed. 

While "Taray" is defined as tamarisk in the more 

modern Spanish-English dictionaries published in the 

United States, it is not so defined in some dictionaries 

and botanical works published in Mexico. Ramirez 

(1902) gives two different species under the heading 

"Taray." In Vera Cruz the legume Oaesalpinia 

bonducella Roxb. is called Taray, while in "varios 

lugares" (other places) Eysenhardtia amorphoides 

H.B.K., also a legume, is known as Taray. Standley 

( 1920), in describing a species of willow Salim ta:nifolia 

H.B.K., notes that in the State of Durango it is called 

"Taray" or "Taray de rio" while in Chihuahua it is 

called "Tarais." Salim taJdfolia occurs along streams 

and washes throughout Mexico, south to Guatemala, 

and in the United States from western Texas to Arizona. 

Inasmuch as this species of willow was common in much 

of the country traversed by Father Escalante, it seems 

probable that when referring to the plant in his journal 

he would use the local name "taray ," meaning willow 

and not tamarisk. 

According to Christensen (1962, p. 53), "tamarim was 

not recorded by the early explorers who traveled on 

the Green and Colorado Rivers in Utah" in the period 

from about 1869 to 1875, or by earlier explorers who 

also crossed these rivers. 

The first introduction of tamarisk into the United 

States appears to have been by nurserymen in the early 

1800's. In 1823 according to Horton (1964, p. 2) "tamarisk was offered for sale in New York City by the 

Old American Nursery operated by Lawrence & Mills," 

and in 1828 by Bartram's in Philadelphia. During the 

1830's it was listed by several nurseries along the 

eastern seaboard. 

Later the U.S. D·epartment of Agriculture began 

growing tamarisk and in 1868 their annual report (p. 

123) listed six species that had been established in the 

Department's Arboretum Grounds in Washington, 

D.C. (Horton, 1964, p. 2). Between 1871 and 1890 a 

large number of collections of tamarisk were made 

from the plants growing in the arboretum. Apparently 

many plants were growing there before collections were 

made outside of Washington. The source of the stock 

is not known; the plants may have been imported or 

they may have been obtained from local nurseries. 

The earliest· authentic record of Tamarim in the 

Western States of which the author is aware is found in 

the catalogs of early-day nurseries. Bowser (1958, 

p. 14) notes that California firms listed T amari:», 

species unknown, as early as 1856. Dr. H. M. Butterfield, agriculturist emeritus, Agricultural Extension 
A4 STUDIES OF EVAPOTRANSPIRATION 

Service, University of California, reports (written commun., 1963) that Tamarim was available in California 

from nursery stock of the Highland Nurseries of New 

York as early as 1854. Dr. Butterfield, who has an 

extensive collection of early-day nursery catalogs, has 

the following to say concerning the early listing of 

Tamariw: 

Some eastern nurseries were listing Tamari:JJ before we had 

records in California. Most of our early introductions into California came from nurseries in New York and other States. 

The old Downing Nursery at Newburg, N.Y., was taken over 

by the Saul family and in 1854 the Highland Nurseries operated by the Saul family listed Tamarim gallica, T. germanica 

and one called T. libanotis ( p. 47 of their 1854-55 nursery 

catalog). James Saul was sent to California to represent the 

nursery and was in San Francisco in 1854 and later. * * • 

A. P. Smith, of the Pmnological Garden and Nursery 

in Sacramento, in his 1856 nursery catalog (p. 14) 

listed T. africana and T. gallica. 

The Suscol Nursery, operated by the Thompson 

Brothers at Suscol, Calif., as early as 1856 on, listed 

two kinds of Tamarim in 1861-African and German 

(p. 29 of 1861-2 catalog). (Suscol, now abandoned, 

was located about 6 miles south of Napa, Calif., and 

1 mile west of State Highway 29 between Vallejo and 

Napa.) 

Ja.mes Hutchison, of the Bay Nurseries in Alameda, 

in his catalog for 1874-75, on page 34 listed Tamariw 

gallica, while R. D. Fox, of the Santa Clara Valley 

Nurseries north of San Jose, in the 1884 catalog, page 

23 listed Tamariw africana and T. chinensis. 

In discussing the species listed in these catalogs Dr. 

Butterfield points out the uncertainty of the proper 

names or synonyms given in the early listing. He feels 

that an opinion on synonyms should be based on what 

was probably grown rather than on present-day name 

usage. Because of the similarity in appearance, he 

thinks T. afrieana may have been confused with either 

T. parvifiora or T. gallica and that T. parviflora has 

often be.en confused with T. africana and T. galliea. 

There has indeed been much confusion of nomenclature for the deciduous species. McClintock ( 1951) has 

shown that the species common in Arizona and New 

Mexico is T. pentandra Pallas rather than T. galliea 

Linnaeus as formerly thought (Kearney and Peebles, 

1942), and this interpretation was accepted in the later 

work of Kearney and Peebles (1951). 

It is apparent that tamarisk stock was available for 

distribution in the Western States as early as 1854 from 

nurseries in California, and from the Department of 

Agriculture Arboretum in Washington, D.C., in the 

1870's. Although tamarisk stock was available from the 

eastern seaboard nurseries as early as 1823, it seems most 

likely that the role of these nurseries would be as suppliers to the western nurseries, rather than as direct 

distributors. 

Regardless of the possible avenues by which tamarisk 

may have come to the Western States, the best evidence points to its escape from cultivation in the 

1870's. Support for this theory is found in the dates 

of the early collections. The earliest collection-T. gallica-of which the author is aware was in 1877 at Galveston, Texas. T. tetrandra appeared as a cultivated 

plant in 1880 at St. George, Utah. T. pentandra, however, may not have arrived until1890. 

Information pertaining to the time and place of specimen collection is valuable in dating the introduction of 

tamarisk in an area. It is also valuable in following 

the spread of the plant from one area to another. For 

this purpose a list of tamarisk specimens collected in the 

Western States has been prepared, showing the dates of 

collection in chronological order, the collector, and the 

locality where collected. The present location of the 

specimen is given when known. (See table 1.) 

TIME OF GENERAL AWARENESS OF SALTCEDAR IN 

THE SOUTHWEST 

After the introduction of saltcedar into the Southwest, a considerable period elapsed before residents 

generally became aware of its presence. During this 

period the plants spread and formed stands of such 

size as to become noticeable. It was in the 1920's when 

those who lived close to nature-stockmen, farmers, 

sportsmen-began to realize that a new plant had made 

its appearance and gained a foothold in the stream 

valleys of the Southwest. That it was a consumer of 

ground water was not recognized at that time, nor for 

nearly 20 years thereafter. No mention is made of 

saltcedar by Dr. 0. E. Meinzer in his classic paper 

"Plants as Indicators of Ground Water," published in 

1927 as U.S. Geological Survey Water-Supply Paper 

577, nor in an unpublished paper given before the Geological Society of Washington in 1922 by Professor 

G. E. P. Smith, of the University of Arizona, who during the period 1915-25 observed and studied plants that 

were users of ground water. 

The earliest eyewitness report of saltcedar on the Gila 

River in Arizona comes from Ernest Douglas (written 

commun., 1962) of the Arizona Farmer-Ranchman, 

Phoenix. He recalls that it was about 1898 when his 

father, a cowman, brought home a switch of a new 

plant he had found growing in a sandbar along the 

Gila River. The switch was stuck in the moist soil at 

the edge of a ditch that ran by the house; it grew and 

in a season or two became a considerable clump of saltcedar. The ranchhouse was located about 6 miles north 

of Gila Bend, Ariz., and about 1 mile from the Gila 
SALTCEDAR IN THE WESTERN STATES A5 

TABLE 1.-Tamarix speoimens collected in the Western States (1877 to 1920) 

[Specimens in the National Herbarium of the Smithsonian Institution at Washington, D.C. (a) were examined and identified by Jerome S. Horton, U.S. Forest Service. 

Specimens in the Arnold Herbarium of Harvard University (b) were examined and identified by Elizabeth McClintock, California Academy of Sciences. Specimens in the 

Stanford University Herbarium (c). Specimens in the University of Ariwna Herbarium (d) and Pamona College Herbarium (e) were examined and identified by Miss McClintock, John E. Flood, Botany Department, Arizona State University, and Jerome S. Horton. Specimens in the California Academy of Sciences (f) were ex- amined and identified by Miss McClintock. Specimens without sufficient floral parts for positive identification are indicated with a question mark] 

Date Species Collector 

Apr. 1877 _ ------------------------ T. gallica (a) ______________________ J. F. Joor ----------------------------- Sept. 16, 1871---------------------- _____ do_____________________________ L. F. Ward __________________________ _ Apr. 14, 1880---------------------- T. tetran_dra (e) ____________________ Marcus E. Jones _____________________ _ 1888------------------------------- T. tetrandra (a) ___________________ Mrs. M. L. Nash ____________________ _ May 15, 1892 ___________________________ do _____________________________ J. W. Tourney _______________________ _ 

June 10,1893---------------------- T. pentandra (d) __________________ J. J. Thornber------------------------

Mar. 30,1894---------------------- T. tetrandra (a)------------------- M. E. Jones.------------------------- Apr. 5, 1894.---------------------- _____ do __________________________________ do ________________________________ _ Apr. 9-12, 1894____________________ T. gallica (a, d) ____________________ A. A. Heller __________________________ _ 

May 5, 1894_______________________ T. tetrandra (e)____________________ M. E. Jones.-------------------------

May 1894.------------------------ T. gallica (a, d)____________________ M. Hapeman_------------------------ Apr.17, 1896---------------------- T. gallica (a, b) ____________________ A. A. and E. Gertrude Heller ________ _ Apr. 1898.------------------------ T. tetrandra (a)_------------------ Mrs. J. M. Milligan __________________ _ Apr. 11, 1899 ___________________________ do_____________________________ W. F. Wight _________________________ _ 

tl~· Oct. 11, ~· 1907 !~~=~~=~~~~~~~~=~=~~=~= _ -------.-------------- _____ ~: ~ar;~if~~~~~~~===~=~~~~== do _____________________________ f;~Fi~~~~~~=~~~~~=~~~~~~~~~~~~ --Blumer_----------------------- July 6, 1909 .. ---------------------- T. pentandra (a) ___________________ I. Tidestrom _________________________ _ 

tr~ 191L______________________________ ~: ~~t===================== T. ~: ~::~:~~r~~t================= tetrandra (a) __ ------------------ !~J=T~:~~~~======================= Elmer Stearns ________________________ _ 

Sept. 8, 1912----------------------- T. gallica (a)______________________ G. L. Fisher--------------------------

May 21, 1913.--------------------- T. gallica (d)______________________ J. J. Thornber ______ ------------------ May 22, 1913---------------------- T. pentandra (d)------------------ _____ do ________________________________ _ 1913 _________ ------- _______ ------ _______ do __________________________________ do ________________________________ _ 1913 _______ _ .:__ _ __ __ ____ __ __ __ _ __ __ T. gallica (d) ___________________________ do ________________________________ _ 

Sept. 12, 1913---------------------- T. pentandra (d)_----------------- S. B. Parish ___ ----------------------- Oct. 13, 1913.--------------------- T. pentandra (a) ___________________ J. N. Rose and W. R. Fitch.---------

Mar.19, 1914---------------------- T. tetrandra (f) ____________________ John I. Carlson ______________________ _ 

~ ~~~i.:~~~~~~~~~~~~~~~~~~~~ f ~]~~;~~~~~~~~~~~~~~~~~~~ -ti~~~l~~-~::~--~:~~~t:~~ 

Location and Remarks 

Galveston Island, Tex. (naturalized). 

Galveston, Tex. 

St. George, Utah (cultivated). 

Texas. 

Catalina Mts., Ariz. 

Brookings, S.Dak. (cultivated). 

Harrisburg, Utah. 

Beaver Dam, Ariz. 

Corpus Christi, Tex. 

Silver Reef, Utah. 

Galveston, Tex. 

Cliff House, San Francisco, Calif. 

Bonham, Tex. 

Stanford Arboretum, Calif. 

Tempe, Ariz. (common in river bottoms). 

Galveston Island, Tex. 

Barstow, Tex. 

Thatcher, Ariz. . Wilgus Ranch, Chiricahua Mts., Ariz. 

Kanab, Utah (cultivated). 

Winslow, Ariz. (cultivated). 

Univ. Ariz. campus, Tucson, Ariz. 

Nara Visa, N.Mex. (cultivated). 

El Paso, Tex. (cultivated). 

Galveston, Tex. 

Univ. Ariz. campus, Tucson, Ariz. 

Do. 

Univ. Ariz. campus, Tucson, Ariz. (5 sheets). 

Univ. Ariz. campus, Tucson, Ariz. (2 sheets). 

Salton Sea, Calif. 

Pecos City, Tex. 

Agua Caliente, Ariz. 

Univ. Ariz., Tucson, Ariz. 

Havilah, Kern County, Calif. 

Univ. Ariz., Tucson, Ariz. 

Wilmington, Calif. Ontari«_?~,. Calif. 

Hope, N. Mex. 

Salton Sea, Calif. 

River. By 1902, when his family left the ranch, an 

occasional saltcedar could be seen along the Gila River, 

but the species was not well established. 

The time of awareness of saltcedar appears to have 

varied from place to place. Although records (Eakin 

and Brown, 1939, p. 11-18) indicate the presence of a 

few seedlings growing on the delta of Lake McMillan 

on the Pecos River, N. Mex., in 1912, it was not until 

the late 1920's that the growth commanded attention. 

Mr. L. E. Foster, Superintendent of the Carlsbad Project, describes the1 conditions in the delta area of Lake 

McMillan under date of July 20, 1928, as follows (McDonald and Borland, written commun., 1955, p. 51-52): 

common. In 1931 his father pointed out a seedling on 

a road crossing of the Rio Galisteo between Albuquerque 

and Santa Fe, and remarked that "given time, tamarisk 

will cover such channels extensively, as it propagates 

rapidly." 

"At the present time, the entire upper end of the reservoir is covered with a dense growth of tamarisk except 

for a few narrow channels." 

In the Rio Grande valley, the time of general a wareness was about 1930. The earliest report of saltcedar 

growth was in 1910 near Mesilla Park, N.Mex. (Thompson, 1958, p. 2) . Reports by residents of the valley indicate that the plant was uncommon throughout the 

1920's and in the early 1930's. 

Dr. Luna B. Leopold (written commun., 1960) of the 

U.S. Geological Survey, recalls that his father planted 

a tamarisk in front of their house in Albuquerque, N. 

~{ex., about 1920, and that the plant was rather unMr. C. C. McDonald (written commun., 1962) of the 

U.S. Geological Survey, remembers that in 1923, when 

his family moved from a farm on the left bank of the 

Rio Grande west of Old Albuquerque, there was some 

saltcedar growing along an irrigation canal, but none 

along the river. The recollection of saltcedar stands 

out because of the difference between limbs and twigs 

of willow and saltcedar when used as fishing poles and 

for whistles. Willow was very common, having been 

planted for bank protection, but saltcedar was available 

at only one spot. 

Mr. C. L. McGuinness (written commun., 1960), 

also of the U.S. Geological Survey, reports that his 

father, a lifetime resident of the Rio Grande Valley, 

recalls that "as late as October 1931 there were no saltcedars in the vicinity of the 'lakes' southwest o£ Las 

Nutrias, N. Mex." Mr. McGuim:iess, senior, a sportsman, visited this area frequently as he was part owner 

and used certain of these lakes for duck hunting. 

Despite plantings for erosion control in 1926 in 

the tributary streams Rio Salado and Rio Puerco, and 
A6 STUDIES OF EVAPOTRANSPIRATION 

perhaps in other localities, the plants did not become 

important in the plant life of the Rio Grande Valley 

for nearly 10 years. There was no mention of saltcedar in a land-classification report by the Middle Rio 

Grande Conservancy District (McDonald and Borland, 1955, p. 19) in 1926, although other vegetation 

was shown. In 1936, the vegetation of the Rio Grande 

Valley was mapped by the Department of Agriculture during the Rio Grande Joint Investigation (National Resources Committee, 1938). Although saltcedar 

was present in the valley and was mapped on field 

sheets, no separate classification was established; it was 

included under the heading "Trees-bosque." 

The author, who was in charge of the ground-water 

studies in the Colorado portion of the joint investigation, has no recollection of any saltcedar in the San 

Luis Valley or elsewhere in the headwaters of the Rio 

Grande in 1936. 

In the upper Gila River valley in Arizona, saltcedar may have made its presence known a little before 

1920. Mr. Thomas Maddock, Sr. (written commun., 

1960), of Safford, Ariz., notes that longtime residents 

of the Safford Valley date the appearance of saltcedar from the floods of 1916. The floods caused channel shifts of as much as three-quarters of a mile and 

denuded large areas of native vegetation. Shortly 

afterwards, saltcedar was observed growing in the area 

that had been flooded and denuded. 

Gillespie Dam on the lower Gila River was completed 

in 1921. Mr. Thomas Maddock, Jr. (written commun., 

1962), reports that by 1929 the lake back of the dam had 

filled with sediment and a very heavy growth of vegetation had taken place over most of the reservoir area. 

Much of this vegetation was saltcedar. Water losses 

from the Gila River were so great that in 1929 tho 

Gillespie Land and Irrigation Co. began the construction of a drainage ditch on the west side of the river 

to move water from the end of the Arlington Canal to 

the face of the dam. In 1931 this drain was extended to 

a point near the Hassayampa River. This effort is 

perhaps the first known in Arizona to salvage water 

normally lost by saltcedar through evaporation and 

transpiration. 

Saltcedar appears to have been widely used as hedges 

prior to 1920. Mr. Thomas Maddock, Jr., recalls a 

hedge in front of the family home in Williams, Ariz., 

in 1913. Mr. C. L. McGuinness remembers a well-grown 

hedge several years old around their house in Albuquerque in 1921. The species is not known. W. W. Hastings of the U.S. Geological Survey recalls a hedgeplanting of saltcedar in 1919 at the U.S. Agricultural 

Experiment Station in Sacaton, Ariz. 

Mr. Ernest Douglas (written commun., 1962), who 

left the lower Gila Valley in 1902, returned in 1925 and 

"for the next four years edited a paper at Mesa, Ariz., 

but never heard saltcedar mentioned, though it must 

have heen common along the river bottom." In 1929, 

after becoming editor of the Arizona Farmer-Ranchman, he noted that saltcedar had become a hard-tofight nuisance along unlined laterals of the Roosevelt 

Irrigation District in the Buckeye area and that there 

were jungles of it along the Gila River. Even then, he 

writes, no one recognized it as a consumer of precious 

water. 

OCCURRENCE, SPREAD, AND DENSITY OF SALTCEDAR 

GROWTH 

Although the information on the occurrence of saltcedar prior to 1920 is meager, it is sufficient to indicate 

that the plant did not command much attention in the 

43-year period between 1877, when the first specimens 

were collected in Texas, and 1920. This period of the 

plant's history contrasts sharply with the next 40 years, 

when saltcedar was recognized first as a new plant and 

later as a problem plant. During this latter 40-year 

period it spread rapidly from one watershed to another 

and up and down the stream valleys of the Southwest, 

then northward into the Great Basin and the Rocky 

Mountains. In 1961, as shown by plate 1, saltcedar was 

widespread in Arizona, New Mexico, Texas, Oklahoma, 

Kansas, Colorado, and Utah. Small hut well-established areas of growth occur in California, Nevada, 

Oregon, Idaho, Montana, Wyoming, South Dakota, and 

Nebraska. So far as could be ascertained, the plant does 

not occur naturally in Washington and North Dakota. 

Data on the rate of spread prior to 1920 is limited to 

the delta area of Lake McMillan on the Pecos River in 

New Mexico. There are no records or reports of saltcedar in this area prior to 1912. The first report was of 

a few seedlings in 1912 (Eakin and Brown, 1939, p. 11-

12). By 1915 the plants had spread over an area of 

about 600 acres of delta land (National Resources 

Planning Board, 1942, p. 57). In the next 10 years the 

plants continued to spread over the delta area until 

by 1925 they covered 12,300 acres. 

By 1960 the plants covered an estimated 57,000 acres 

in the 200-mile reach between Alamogordo Dam and the 

New Mexico-Texas State line. Concurrent with the increase in tdtal area, there was also an increase in the 

density and in the cover density (the proportion of 

an area covered or shaded by the vegetation foliage; 

usually expressed as a percent). Thus areas of light 

and medium cover became areas of medium and dense 

cover. The increase in the areas is shown graphically 

in figure 2. 
SALTCEDAR IN THE VVESTERN STATES A7 

60 

50 

en 

w 

0:: 

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FIGURE 2.-Increase in the area of saltcedar growth and cover density 

along the Pecos River in New Mexico between Alamogordo Dam and 

the New Mexico-Texas State line. 

The occurrence and spread of saltcedar in the Rio 

Grande basin of New Mexico has a siinilar history. Although it was first reported in the area south of Mesilla 

Park in 1910 (Thompson, 1958, p. 1502-2), most of the 

available information covers the 80-mile reach from 

Bernardo Bridge to San Marcial. In 1918 this reach 

was included in a topographic and land use survey by 

the New Mexico State Engineer that covered 150 miles 

of the valley from Cochiti to San Marcial. No mention 

is made of saltcedar in the description of the land classification. In describing the "timber" classification the 

survey notes : "The timbered areas are those overgrown 

with timber or brush, usually cottonwoods, willows or 

thorn bushes." 

A cross-valley profile near San Marcial in 1924 noted 

the vegetation, but no mention was made of saltcedar. 

The next survey in point of time was a land -classification 

survey in 1926 by the Middle Rio Grande Conservancy 

District. Here again no saltcedar was reported. 

According to an unpublished report for the U.S. 

Bureau of Reclamation (H. R. McDonald and W. M. 

Borland, written commun. 1955, p. 32-41) dealing with 

saltcedar infestation in the middle Rio Grande Valley, 

there was no significant growth of saltcedar prior to 

about 1926. About that time, erosion was a problem in 

some tributary streams, and plantings of saltcedar seedlings were made in 1926 and 1927 at several places in the 

Rio Salado and Rio Puerco basins and perhaps in other 

localities as an erosion and silt control measure. The 

plants spread rapidly after the flood of 1929 and by 

1936 had covered about 5,500 acres (sum of the planimetered areas of parcels of land shown as saltcedar on 

the maps of vegetative cover. National Resources Committee, 1938), in the Bernardo Bridge-San Marcial 

reach. Vegetative surveys of the reach were made by 

the Bureau of Reclamation in 1947 and again in 1955. 

As part of these two surveys, determinations were 

made, by species, of the cover density and of the height 

component of the foliage. Thus it is possible to make 

comparisons of area of growth, density of growth, and 

volume of foliage. 

This area of saltcedar in 194 7 was 26,300 acres and 

in 1955 was 24,800 acres. The decrease from 1947 to 

1955 was due to clearing about 10,000 acres of saltcedar 

for cultivation. These data indicate an increase of 

rubout 8,500 acres of saltcedar growth in the uncleared 

lands. 

In the 1947 survey, cover densities ranged from 1 to 81 

percent and averaged 19.1 percent, while in the 1955 

survey, cover densities ranged from 2 to 100 percent 

and averaged 39.3 percent, an increase of more than 100 

percent. At the same time the increase in the volume 

of foliage was over 75 percent. 

According to Christensen ( 1962) , there are no records of T amariw at Utah Lake, at Great Salt Lake, or 

on the Colorado and Green Rivel"s in Utah prior to 1925. 

He reports that "the period from approximately 1925 

to 1960 was one of rapid spread and increase in importance of tamarix. The greatest degree of invasion 

occurred during the twenty-year period from about 

1935 to 1955." 

In the Arkansas River valley of Colorado, Bittinger 

and Stringham (1963) found a similar history of increase in the area and cover density of saltcedar growth. 

Comparisons of the areas of saltcedar growth by aerial 

photographs taken in 1936, 1947, and 1957 show quite 

clearly the progressive invasion of saltcedar. As an 

example, in the study reach of the valley the area of 

phreatophytes, largely saltcedar, increased 520 acres in 

the 11-year period from 1936 to 1947, or at an average 

rate of 47 acres a year. In the 10-year period from 

1947 to 1957 the average rate of increase was 57 acres 

a year. Not only was there an increase in area during 

these periods but also an increase in the cover density. 

In the aerial photographs in figure 3, taken in 1936 and 

1957, the increase in area and cover density in the 21-

year period is easily seen. 

Concerning the spread of saltcedar in Kansas, Mr. 

P. H. Berg (written commun., 1962), Project Manager, 

Bureau of Reclamation, states that: 

* * * Because of experience in other reclamation areas in 

the southwest with saltcedar, we have kept a close watch in our 
A8 STUDIES OF EVAPOTRANSPIRATION 

reservoir areas and on irrigation systems for any new infestations of saltcedar that may occur. Within a short period after 

we complete a dam or reservoir, scattered plants of saltcedar 

are observed. Each year we observe a few more plants with 

more mature ones furnishing seed for new infestations. 

It is logical to assume that were data available for 

other stream valleys they would show a history of saltcedar growth and spread similar to that in the Gila, 

Pecos, Rio Grande, and Arkansas River valleys. 

AREAL EXTENT 

The areas of saltcedar growth in the Western States 

as of 1961 are shown on plate 1. Owing to the small 

scale of the map, it is not possible to delimit the actual 

boundaries. Rather the map is diagrammatic, showing 

the reaches of the streams and included reservoirs, lakes, 

and playas where saltcedar is known to occur. In compiling the map, the author attempted to visit and observe areas where saltcedar was unreported, but was 

suspected to be present. However, it was not possible 

to examine all of them, so there may be some areas of 

growth that are not shown. Although these are believed 

to be few, isolated, and small, they do form a seed source 

from which the growth may spread. 

Some observations of saltcedar growth were made at 

the road crossings of streams, and were limited to the 

growth seen from the road. The sites of these observations are shown by means of a distinctive symbol on the 

map. Owing to the aggressive nature of the plant, 

growth may be suspected for a considerable distance up 

and down stream from the crossing. Lacking confirmation of this, however, the presence of growth at the 

crossing only is indicated on the map. 

The largest area of saltcedar, 275,000 acres, occurs 

in the Pecos River basin of New Mexico and Texas. It 

was estimated by the Geological Survey ground-water 

office in Albuquerque that in 1960 some 57,000 acres 

in the New Mexico portion of the basin was infested. 

In the Texas portion, on the basis of a general reconnaissance of the basin by the Soil Conservation Service 

in 1959, there was about 218,000 acres (C. A. Rechenthin, written commun., 1963). In this portion of the 

basin according to Mr. Rechenthin, "saltcedar covers 

most of the bottom lands from the New Mexico line to 

a point below Sheffield, * * * is found on many tributary streams such as Salt Draw, Toyah Creek, Tornillo 

Draw and others * * * and is found extensively on 

'gyp' soils in the Pecos, Imperial, Fort Stockton and 

Girvin areas." ' 

The cover density, according to J. S. Horton (written commun., 1962) is quite variable, ranging from 5 

~o 100 percent. The area of dense growth, occurring 

In the flood plain adjacent to the Pecos River channel, 

was estimated at about 15 percent of the total area of 

the Texas portion of the Pecos basin. In the remainder 

of the area the cover density had decreased in the fall 

of 1962 to 5 to 15 percent. Horton reports that in these 

areas the shrubs are suffering and some have died as 

the result of either increased salinity in the ground 

water or a declining ground-water level. 

A similar condition prevailed shortly after the close 

of World War II along the Gila River in Arizona for 

a few miles below Gillespie Dam. Here increased 

pumpage for irrigation lowered the water table to such 

an extent that between about 1950 and 1955 much of the 

saltcedar died. This area of growth is not included 

on plate 1. 

No attempt was made to indicate the cover density 

of the growth on the map. The cover density, however, 

as indicated above, is known to range from scattered 

growth of a few percent to 100 percent. Where growth 

along a stream was not continuous but occurred at intervals, it is shown by a broken pattern. 

On the basis of the assembled information, table 2 

was prepared to show the approximate acreage of saltcedar growth by States. The acreage for each State 

is not presumed to be exact but is considered sufficiently 

accurate to indicate the magnitude of the growth area 

in each State. Neither is the total of 900 thousand 

acres presumed to be exact, but it is believed to be a 

realistic indication of the area of saltcedar growth in 

the Western States at the end of the 1961 growing 

season. 

TABLE 2.-Gross areas of saltcedar growth in the Western States as of 1961 

Area 

State (in thousands of acres) 

Arizona______________ e. 118 

California____________ e. 16 

Colorado___________ _ _ 50 

Idaho________________ (b) 

Kansas_______________ 25 

Montana_____________ (b) 

Nebraska_____________ (h) 

Nevada______________ 8 12 

New Mexico__________ 155 

Area 

State (in thousands of acres) 

North Dakota________ 0 

Oklahoma____________ 60 

Oregon_______________ 1 

South Dakota_________ (b) 

Texas________________ c450 

Utah_________________ 38 

Washington___________ 0 

Wyoming_____________ 1 

Total (rounded)_ 900 

a A vegetation survey by the Bureau of Reclamation in 1961 found there was 53,200 acres of saltcedar in the flood plain of the Colorado River from Davis Dam to the 

international boundary, of which 38,000 acres was in Arizona, 12,700 acres in Cali· 

fornia, and 2,400 acres in Nevada. These figures included in the State totals. b Less than 1,000 acres. " A brush survey by tbe Soil Conservation Service in 1963-64 (Smith, H. N. and 

Rechenthin, C. A., 1964) found that as of June 1964 there was a total of 523,900 acres of saltcedar, of which 273,000 acres were dense stands (more than 20 percent ca::wpy), and 250,900 acres were light to moderate stands (less than 20 percent canopy). 

WATER CONSUMPTION 

The term "saltcedar" includes the deciduous species 

described earlier. Saltcedars are phreatophytes; that 

is, they depend upon ground water for their water supply. Their occurrence under natural conditions is confined to areas where their roots can reach the water 
SALTCEDAR IN THE WESTERN STATES A9 

FIGURE 3.- Aerial photograph&, taken in 1936 (uppel'\) un.d in 1957 (lower), of the Arkansas River valley at the Otero-Bent County line, Colo-· 

rado. The areas of scattered cottonwood growth of 1936 have been filled in and were do)llinated by a dense growth of tamarisk in 1957. 
AlO STUDIES OF EVAPOTRANSPIRATION 

table, such as on the flood plains of stream valleys, on 

deltas, or along the shoreline of lakes and reservoirs. 

The plants usually grow where the depth to the water 

table does not exceed 25 feet, and normally where it is 

less than 15 feet. Saltcedars have a wide range of 

tolerance to saline or alkali soil and water. They have 

been found growing in Death Valley, Calif., where the 

ground water contains as much as 5 percent ( 50,000 

parts per million) of dissolved solids. However, it 

cannot be said they thrive where the concentration of 

the water approaches the 5 percent limit. Generally 

they grow best where the ground \Vater is little to moderately mineralized. 

Under optimum conditions the annual rate of consumption of ground water by saltcedars is probably the 

highest of all the phreatophytes; The plants have 

a low economic value, and hence the water used by 

them is largely wasted. The term "consumptive 

waste" (that part of consumptive use that is without 

substantial benefit to man) aptly describes the disposition of this water. 

The annual rate of use of ground water by saltcedar 

depends upon several factors such as cover density, size 

of the plants, depth to the water table, and climatic 

conditions. Use is greatest where the height and density are at a maximum, the water table lies at shallow 

depth, and the climate is hot and dry. 

Studies of the annual rate of use of water by saltcedar show that under favorable conditions it is more 

than 9 acre-feet per acre. Experiments with plants 

grown in tanks in the Safford Valley of the Gila River, 

Ariz., have shown that at 100-percent volume-density 

the annual evapotranspiration discharge, not including 

precipitation, ranged from 9.2 acre-feet per acre when 

the depth to the water level was 4.0 feet to about 7 acrefeet per acre when the water level was at a depth of 

8 feet (Gatewood and others, 1950, p. 137). The average annual use of ground water by saltcedar in the 

Safford Valley, under natural conditions, was 4 acrefeet per acre. The cover density ranged from scattered growth to 100 percent, and averaged 61 percent. 

At Carlsbad, N.Mex., the annual use of water by saltcedar grown in tanks was 5.5 acre-feet per acre with a 

2-foot water level and 4.7 acre-feet per acre with a 4-

foot water level (Blaney and others, 1942, p. 202). 

The average annual use of ground water by saltcedar 

in the Pecos River valley, N. Mex., was estimated, on 

the basis of plants grown in tanks, to be 5.0 acre-feet 

per acre (National Resources Planning Board, 1942~ 

p. 55). 

EFFECT ON STREAM REGIMEN 

The regimen of a stream on whose flood plain saltcedar has become established is usually affected in three 

ways. There is (1) a depletion of streamflow, (2) an 

increase in the area inundated by floods, and ( 3) an 

increase in deposition of sediment in the areas of saltcedar growth. 

As noted earlier, consumption of ground water by 

saltcedar is among the highest of all phreatophytes. 

As a consequence of its draft on the ground-water reservoir, there is a general lowering of the groundwater level throughout the area of growth. Lowered 

ground-water levels affect streamflow either by reducing 

ground-water movement toward a gaining stream or by 

increasing percolation from a losing stream to the 

ground-water reservoir. In either case the result is the 

same-a reduction in streamflow. 

In a well-established area of saltcedar along a stream, 

the plants grow so densely that they choke overflow 

channels and the flood plain, and so form a partial 

barrier to flood flows. During periods of flood, this 

restriction and increased channel roughness cause the 

water to spread out and inundate areas that normally 

would not be flooded and thus to endanger lives and 

damage property. 

Floodwater is nearly always laden with sediment. 

The damming or ponding effect of the dense saltcedar 

growth so reduces the velocity of the water, and thus 

its power to carry the :full sediment load, that much 

of the sediment is dropped and deposition is accelerated. 

Substantial deposition of sediment attributed to saltcedar growth has occurred in the Rio Grande and Pecos 

Rivers in New Mexico and the Gila River in Arizona. 

Sediment deposition resulting in part :from saltcedar 

growth is common in the delta areas above reservoirs. 

FUTURE CONSIDERATIONS 

The history of the invasion of saltcedar in the Western States provides a basis :for forecasting its :future 

performance and estimating its areal extent and consumptive waste of ground water. 

Historically, the area and the density of plant 

growth have increased wherever the species has become esta,blished. This effect may be expected to continue, wherever area and density of growth have not 

reached their optimum and wherever new areas become 

established. At the same time, increased consumptive 

waste of ground water, increased flood hazards, and 

continued sediment deposition may be expected. 

The increase in area and density will not be at the 

same rate everywhere, but will vary :from place to 

place according to the availability of growing space 

and to environmental conditions, such as climate, depth 

to ground water, and degree of alkalinity or salinity. 

In the stream valleys that now support extensive 

growth, such as those in Arizona and New Mexico 
SALTCEDAR IN THE VVESTERN STATES All 

where there is little room for expansion, the areal increase will not be large. The density, however, will 

continue to increase until optimum growth prevails 

throughout the area. Although no saltcedar was reported in the States of North Dakota and Washington 

in 1961, it is reasonable to expect the plant to make its 

appearance in the near future. 

If it is assumed that no control measures will be taken 

to curb the spread and continued growth of saltcedar, 

some predictions can be made of the magnitude of the 

growth area and the consumptive waste of ground 

water. 

The area of saltcedar growth at the tiine of a wareness of its presence in 1920 must have been small. The 

meager data indicate that the growth area was about 

10,000 acres. Most of this growth was on the delta 

of Lake McMillan on the Pecos River, N. Mex. By 

1961 the area had increased to about 900,000 acres, or at 

an average rate of about 22,500 acres a year. Projection 

of this rate over the 9-year period to 1970 indicates an 

increase of about 200,000 acres. The average rate of 

increase, however, is much less than the maximum rate. 

The two areas for which information is available on the 

average and maximum rates of spread, the Pecos River 

valley in New Mexico and the Arkansas River valley 

in Colorado, show that the maximum rate occurred in 

the decade 1950 to 1960. Thus an increase of 200,000 

acres to a total of 1,100,000 acres in the 17 Western 

States by 1970 would be a minimum. 

In the Pecos River valley the average rate of increase from 1915 through 1960 was about 1,250 acres a 

year. The rate during the period 1950 to 1960 was 

double the long-term average, or about 2,500 acres a 

year. 

The saltcedar growth in the Pecos River valley during the 10-year period 1950 to 1960 increased by 25~000 

acres, as shown in figure 2. This is 78 percent of the 

area covered in 1950. In the Arkansas River valley the 

increase from 194 7 to 1957 was about 81 percent of the 

1947 area. In the Rio Grande Valley, the increase in 

the period 1947 to 1955 would have been about 32 percent of the 1947 area, had there been no clearing. Expressed as average rates per year, they are 7.8, 8.1, and 

4.0 percent respectively. Projection of these average 

yearly rates over the 9-year period from 1961 to 1970 

indicates an increase in the total area of saltcedar of 

325,000 to 650,000 acres. 

On the basis of these estimates of the minimum and 

the average yearly increase in total area of saltcedar 

growth by 1970, the increase would range from 200,000 

acres to 650,000 acres. The average of these projections 

indicates a probable increase of 425,000 acres, or a 

total of about 11j3 million acres by 1970. 

The average annual use of ground water by saltcedar 

in the Safford Valley, Ariz., was 4 acre-feet per acre, 

and in the Pecos River valley it was 5 acre-feet. On 

the basis of an average of 4.0 acre-feet for the entire 

region, the annual draft on the ground-water reservoir 

in 1961 was about 3.5 million acre-feet and in l970 

would be about 5 million acre-feet. In 1920 the draft 

probably did not exceed 50,000 acre-feet. 

These predictions, as stated earlier, have been made 

to indicate the magnitude of the saltcedar problem by 

1970 and its effect on water supply, under the assumption that the spread and growth of the species will not 

be curbed by control measures. 

REFERENCES 

Auerbach, Herbert S., 1943, Father Escalante's Journal, with 

related documents and maps: Utah Hist. Quart., v. 9, 

p. 1-142. 

Bittinger, M. VV., and Stringham, G. E., 1963, A study of phreatophyte growth in the lower Arkansas River valley of 

Colorado: Colorado Univ. Civil Eng. Sec., Colorado Agr. 

Expt. Sta. 

Blaney, H. F., Ewing, P. A., Morin, K. V., and Criddle, VV. D., 

1942, Consumptive water use and requirements, Pecos 

River, New Mexico and Texas, (U.S.) Natl. Resources 

Plan. Board, Pecos River Joint Investigation-Reports of 

the participating agencies: VVashington, U.S. Govt. Printing Office, pt. 3, sec. 3, p. 17~230. 

Bowser, C. W., 1958, Introduction and spread of the undesirable 

tamarisks in the Pacific southwestern section of the United 

States and comments concerning the plants' influence upon 

the indigenous vegetation in Symposium on Phreatophytes, 

Phreatophyte Subcomm. Pacific Southwest Inter-Agency 

Comm. Mtg., Am. Geophys. Union, Sacramento, Calif., 

February 1957: p. 12-17. 

Christensen, E. M., 1962, The rate of naturalization of 

Tamarim in Utah: The Am. Midland Naturalist, v. 68, no. 

1, p. 51-57. 

Eakin, M. E., and Brown, C. B., 1939, Silting of reservoirs: U.S. 

Dept. of AgricUlture Tech. Bull. 524, p. 11-18. 

Gatewood, J. S., Robinson, T. W., Colby, B. R., Hem, J. D., and 

Halpenny, L. C., 1950, Use of water by bottom-land vegetation in lower Safford Valley, Arizona: U.S. Geol. Survey 

Water-Supply Paper 1103,210 p. 

Horton, J. S., 1957, Inflorescence development in Tamwrirc pentandra Pallas (Tamaricaceae) : Southwestern Naturalist, 

v.2,no.4,p.135-139. 

--1964, Notes on the introduction of deciduous tamarisk : 

U.S. Forest Service Research Note RM-16 (March 1964). 

Kearney, T. H., and Peebles, R. H., 1942, Flowering plants and 

ferns of Arizona: U.S. Dept. Agriculture Misc. Pub. 423, 

1069p. 

--1951, Flora of Arizona: California Univ. Press, 1032 p. 

McClintock, Elizabeth, 1951, Studies in California ornamental 

plants ; 3 The Tamarisks : California Hort. Soc. Jour. 12 

p., 76-83. 

Ramirez, Jose, 1902, Sinonimia vulgory y cientifica de l,as 

plantas Mexicanas : Ofecinca Typografica de la Secretaria 

de Fomento, Mexico. 

Robinson, T. W., 1958, Phreatophytes: U.S. Geol. Survey WaterSupply Paper 1423, 84p. 
A12 STUDIES OF EVAPOTRANSPIRATION 

Smith, H. N., and Rechenthin, C. A., 1964, Grassland restoration 

the Texas brush problem: U.S.D.A. Soil Conservation Service, Temple, Texas. 

Standley, Paul C., 1920, Trees and shrubs of Mexico: Contributions from the U.S. Natl. Herbarium, Smithsonian Inst., v. 

23, pt. 1. 

Thompson, C. B., 1958, Importance of phreatophytes in water 

supply: Am. Soc. Civil Engineers, Jour. Irrig. and Drainage 

Div. Proc., v. 84, no. 1R1, p. 1502-1-1502-17 (January 

1958). 

[U.S.] National Resources Committee, 1938, Regional planning; 

Pt. 6, The Rio Grande joint invest~gation in the Upper Rio 

Grande Basin in Colorado, New Mexico, and Texas, 1936-

37: Washington, U.S. Govt. Printing Office, v.l. 

[U.S.] National Resources Planning Board, 1942, Regional 

planning; Pt. 10, The Pecos River joint investigation in 

the Pecos River Basin in New Mexico and Texas, Summary analysis and findings: Washington, U.S. Govt. 

Printing Office. 

U.S. GOVERNMENT PRINTING OFFICE: INS 0-757·NI