Composition of Saline 

Residues on Leaves and 

Stems of Saltcedar 

(Tamarix pentandra Pallas) 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 491-C 

Composition of Saline 

Residues on Leaves and 

Stems of Saltcedar 

(Tamarix pentandra Pallas) 

By JOHN D. HEM 

STUDIES OF EVAPOTRANSPIRATION 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 491-C 

Analyses of saline deposits leached or washed 

from saltcedar plants 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEW ART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

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

Washington, D.C. 20402 - Price 20 cents (paper cover) 
CONTENTS 

Abstract __________________________________________ _ 

Uptake and circulation of inorganic ions by plants _____ _ Collection of data __________________________________ _ 

Interpretation of results ______________________ ----- __ 

Nature and amount of solutes ___________________ _ 

Page 

C1 

1 

2 

6 

6 

Pa~te 

Interpretation of results-Continued 

Relation of leached solutes to ground-water quality__ C6 

Effects of other factors__________________________ 7 

Conclusions---------------------------------------- 8 

Literature cited_____________________________________ 9 

ILLUSTRATION 

Pag& 

FIGURE 1. Graph showing average sulfate to chloride ratio in solutes washed from saltcedar leaves, Pecos River basin, 

N. ~eX------------------------------------------------------------------------------------------ CS 

TABLES 

Page 

TABLE 1. Composition of solids leached from saltcedar leaves; 16 to 24 hours contact time_____________________________ C3 

2. Composition of solids washed from saltcedar leaves, few minutes contact time, and of solids dissolved in nearby 

water-------------------------------------------------------------------------------------------- 4 

3. ~iscellaneous analyses of water associated with saltcedar------------------------------------------------- 6 

m 

236-478-66 

STUDIES OF EVAPOTRANSPIRATION 

COMPOSITION OF SALINE RESIDUES ON LEAVES AND STEMS OF SALTCEDAR 

(TAMARIX PENTANDRA PALLAS) 

By JoHN D. HEM 

ABSTRACT 

Saltcedar leaves and stems collected along the Gila 

River in Safford Valley, Ariz., and at various locations 

in the Rio Grande and Pecos basins of New Mexico, were 

analyzed for inorganic ions. The total content of calcium, magnesium, sulfate, and chloride in the leaves 

generally ranged between 5 and 15 percent of their dry 

weight. From a few tenths of a percent to more than 

3 percent of the dry weight of the leaves consisted of 

inorganic ions which could be washed off by rainfall. 

In most samples, the predominant inorganic anion was 

sulfate. Leaves highest in sodium and chloride content 

were obtained from trees growing where ground water 

had a high salinity. 

The amounts and composition of inorganic solutes 

which are present in saltcedar leaves are influenced by 

numerous factors including composition of water available to the plant, the time of year, the rates of growth 

and transpiration before sampling, and the amount and 

frequency of antecedent rainfall. 

UPTAKE AND CIRCULATION OF' INORGANIC IONS BY 

PLANTS 

The processes whereby plans absorb inorganic ions 

from soil solutions and the means which certain species 

of plants have for coping with excessive salinity in 

water and in soil have been studied for a long time. The 

published literature on these subjects, however, indicates 

that although some understanding has been gained, the 

details of the processes involved are far from being completely understood. 

Some of the major constituents dissolved in natural 

water, in particular calcium, magnesium, sulfur, and 

carbon, are essential for plant growth. Most of the 

carbon required for carbohydrate synthesis is taken 

from atmospheric carbon dioxide, however, and the oxygen and hydrogen required are supplied from the water 

itself. Chlorine is required for plant growth only in 

small quantities and sodium apparently is essential for 

some but probably not all plants. Other essential elements such as iron are commonly present in smaller 

amounts in natural water (Sutcliffe, 1962, p. 6). It is 

to be expected that plant parts where metabolic processes are actively taking place, especially the leaves, 

would contain all the elements needed by the plants. 

Other elements extracted with the nutrients from the 

medium in which the plant is growing also might be 

present. Some plant species are noted for their tendency to accumulate elements present in minor amounts 

in the soil. Certain species of Astragalus, for example, 

accumulate selenium in large amounts (Anderson and 

others, 1961, p. 35). 

Sutcliffe (1962, p. 5) presented data he had obtained 

from the literature showing that specimens of stonewort 

Ohara ceratophylla, contained similar amounts of calcium, magnesium, and potassium regardless of the composition of the medium in which they were grown but 

that amounts of sodium and chloride taken up did depend to some extent on the concentration of these elements in the available water. He commented, "In particular, sodium is present at a low concentration in the 

above-ground parts of many plants, irrespective of the 

amount of sodium in the soil * * * ." Evidently some· 

plants reject sodium, and others may take it up only 

incidentally in obtaining other nutrient ions. 

Saltcedar is the common name applied to two deciduous species of the genus Tamari'lJ (T. pentandra Pallas and T. gallioa Linnea us) which have become nuisance plants along streams in parts of the Western 

United States (Robinson, 1965). One of the distinctive 

traits of the saltcedar is its ability to thrive in areas 

where the ground water, from which its water requirements are met, has a rather high dissolved-solids concentration. The plant does not appear to be a true. 

halophyte in the sense that it requires a saline environment, but it can thrive in places where the growth of 

01 
C2 STUDIES OF EVAPOTRANSPIRATION 

most other vegetation is strongly inhibited and thus 

shares some of the properties of the halophytes. 

The assimilation of water by plant roots involves the 

passage of water molecules through root membranes by 

osmosis, movement of water being toward the solution 

of higher solute concentration. Some solute ions pass 

with the water through the root membranes and generally supply the nutrient needs of the plant. 

To obtain water from the soil, plants must ov.ercome 

two forces. The first of these, soil-moisture tension, 

causes water films to adhere to soil particles. The other 

force is the osmotic pressure required to separate solvent 

molecules from a solution, and this force increases as 

the concentration of dissolved solids in the solution rises. 

Thus, as the salinity of available water around a plant's 

root system increases, the osmotic pressure required to 

extract water molecules becomes greater and greater. 

If the salinity of the soil water is too great, the plant 

will succumb from lack of water because it is unable to 

attain a high enough osmotic pressure. 

Halophytic plants in general can exert a high osmotic 

pressure. According to Sutcliffe (1962, p. 156), this 

is mainly because of high sodium and chloride content 

of the cell sap. In some plants of this class, the salt 

concentration of the cell sap rises throughout the growing season, but in others the concentration is maintained 

at a fairly constant level by certain regulatory mechanisms. The presence of large amounts of water in the 

tissues of succulent plants is one mechanism for preventing excessively high dissolved-salt concentrations within the plant. Many halophytes are succulent plants. 

More freely transpiring halophytic plants, however, 

require other mechanisms. Certain plants, including 

saltcedar (Decker, 1961), have organic structures termed 

"'salt glands" on their leaves which can excrete fairly 

concentrated solutions. The salt in this solution is left 

behind on the leaf surface when the water is evaporated 

.and may be washed from the plant by rain or blown off 

hy wind. 

The manner in which salt glands remove or concentrate salt from the internal solutions of the plant is not 

fully understood, although Sutcliffe (1962, p. 161) 

thought it probable that the glands perform osmotic 

work. If so, the plant actually expends energy in the 

process of eliminating salt. A fairly detailed anatomi-

·cal description of the salt glands of saltcedar has been 

given by Campbell and Strong (1964). 

Another process by which a plant may rid itself of 

·saline material is the process of guttation. When tran-

·spiration ceases, at the end of the day, the solutions in 

the plant circulatory system may continue moving upward and outward to leaf surfaces, and drops of moisture may thus appear on the leaves. This moisture, 

although i't has the appearance of dew condensed from 

the atmosphere, can be highly charged with salt derived 

from residues left in the leaf structures from the day's 

transpired solution, as well as from residues on the 

leaves from the activities of the salt glands and the 

evaporation of prior guttation. 

The green leaves of saltcedar plants commonly carry 

small cubic crystals which are readily seen with the aid 

of a hand lens. Although the appearance of the crystals 

suggests they are nearly pure sodium chloride, the salt 

brought to the leaf surfaces also includes considerable 

amounts of other ions. The salt is transferred to the 

ground by rainfall or wind. Actual quantities of salt 

involved in such transfer mechanisms in areas of dense 

saltcedar growth have never been determined. Qualitative evidence includes the absence near saltcedar of 

vegetation having a low salt tolerance and the high corrosion rate of metals exposed in saltcedar thickets. 

Decker (1961) noted the salt crystals on the foliage of 

saltcedar and the formation of whiskers of salt at the 

sites of the salt glands on the leaf surfaces. In his experiments, these salt deposits proved to be deliquescent 

and went into solution when the twigs were exposed to 

humid air. Drying caused cubic salt crystals to form 

on the leaves. Decker believed the liquid observed on 

saltcedar leaves in the field, which had been ascribed to 

guttation (Gatewood and others, 1950) , was actually the 

result of the condensation of atmospheric moisture. 

COLLECTION OF DATA 

During investigations of water quality in Arizona 

and New Mexico in which the writer participated in 

the 1940's, the presence of salt crystals on saltcedar 

foilage was noted on many occasions, and from time to 

time several types of experiments were performed on 

samples of foilage to determine the quantity and nature 

of the saline material. The results of these experiments 

were not highly consistent or simply interpretable, and 

most of them were never published. Owing to increased 

interest in the processes whereby salt-tolerant plants are 

able to gr:ow and in the details of the transpiration processes of the saltcedar, the data have been reexamined 

and are presented here as an aid in understanding some 

features of the solute circulation of the saltcedar and to 

aid in planning further studies of the process. 

The samples usually consisted of green leaves and 

associated stems. Some collections were made after the 

end of the growing season when the leaves were no 

longer green, but most specimens were actively growing 

when collected. Generally, a sample of about 25 grams 

was obtained in the field by clipping leaves and stems 

from a single plant. In the studies of 1940 and 1944, 

the samples were brought to the laboratory and allowed 
CO:M:POSITION OF SALINE RESIDUES ON LEAVES AND STEMS OF SALTCEDAR C3 

to dry in the open air. About 2 g of this material was 

then oven dried at 110° C for 1 or 2 hours. The weight 

loss from oven drying, generally between 10 and 15 

percent, was ascribed to moisture not removed by air 

drying. The plant material lost most of its green color 

during oven drying, however, so some breakdown of 

the organic material probably also took place. About 

5.0 g of the air-dried material was placed in a beaker, 

100 milliliters of distilled water was added, and the. 

solution stood with occasional stirring for 16 to 24 

hours. In some of the experiments, the leaching was 

done at room temperature; in others, the solutions were 

kept warm on a water bath. The temperature at which 

the leaching was performed did not affect the results 

significantly. 

After the leaching, the solution was filtered and quantitatively transferred to a 250-ml volumetric flask. The 

flask was then filled to the mark with distilled water, 

and the solution was analyzed for calcium, magnesium, 

sulfate, chloride, and bicarbonate content and for total 

dissolved material. Results were calculated as percentages of the air-dried sample weight. 

A large part of the material leached from the leaves 

and stems was organic, and the final solutions generally 

were strongly colored. The inorganic ions which were 

leached probably represented not only the saline deposits on leaf surfaces but also any ions that were present anywhere in the leaf tissues in combination with 

organic ligands. The analytical results are given in 

table 1. 

TABLE 1. Composition of solids leached from saltcedar leaves, 16 to 24. hours contact time 

Percent of air-dried sample 

Sample Residue after Sum Sulfate: Description 1 2 3 4 (1-4) chloride evaporation Calcium Magne- Sulfate Chloride (heated for 1 

hr at 180°C) sium 

A.-Vegetation along Pecos River between Artesia and Carlsbad, N.Mex., sampled Marc:h 4-7,1940 

1 29.5 ---------- ---------- 4.9 2. 7 ---------- 1. 8 New growth on tree at bridge on New Mexico Highway 83, east of Artesia, N.Mex. 

2 17.1 ---------- ---------- 3.1 2.2 ---------- 1.4 New growth on tree on river bank near Carlsbad Spring, Carlsbad, N. Mex. 

3 29.7 ---------- ---------- 6. 0 2.6 ---------- 2. 3 Dead leaves from previous season on tree at bridge on New Mexico Highway 83, east of Artesia, N. Mex. Average of two samples. 

B.-Vegetation in Safford Valley, Ariz., sampled November 1944 

4 28.5 1. 7 0. 7 5.2 0.8 8. 4 6. 5 Saltcedar growing in tank 16, Glenbar experiment station, Arizona. Water table 

held at 6.0 ft below surface. 

5 26.5 2. 4 .5 7.1 1. 0 11.0 7.1 Saltcedar growing in tank 21, Glenbar experiment station, Arizona. Water table 

held at 6.0 ft below surface. 

6 26.8 1.4 .6 4. 7 .9 7.6 5. 2 Saltcedar growing naturally near tank 16, Glenbar experiment station, Arizona. 

7 26.8 1. 3 .5 5. 4 4.1 11.3 1.3 Saltcedar growing beside drain ditch from Knowles flowing well, Geronimo, Ariz. 

8 23.2 .7 1.2 4.3 1.2 7.4 3.6 New growth on young saltcedar near well18-79, SWMNEM sec. 34, T. 4 S., R. 23 E. 

Graham County, Ariz. 

9 24.2 1.1 1. 0 4.8 1.0 7.9 4.8 Mature growth on saltcedar 16ft tall, SWMNE~~ sec. 34, T. 4 S., R. 23 E. Graham 

County, Ariz. 

10 24.8 .6 . 4 2.1 4.8 7.9 . 4 New growth in area cleared 2 months previously, near Fort Thomas, Ariz. 11 26.8 .9 .8 3.2 4. 2 9.1 .8 Mature growth just outside cleared area near Fort Thomas, Ariz. 

12 26.0 1.4 .7 4. 7 1.8 8.6 2.6 Mature growth on Gila River near Geronimo, Ariz. 

C.-Vegetation in Pecos River basin, N.Mex., sampled November 1944 

13 28.9 2.8 0.9 9. 4 1.6 14.7 5.9 Saltcedar on Pecos River near Frazier, N.Mex., bridge U.S. Highway 70. 

14 31.0 2.2 1.9 8. 7 4. 3 17.1 2. 0 Saltcedar on Pecos River near Artesia, N. Mex., New Mexico Highway 83 bridge. 15 29.9 2. 7 1.1 9. 3 2. 3 15.4 4. 0 Saltcedar on Pecos River near Major Johnson Springs below McMillan Dam, N.Mex. 

16 23.2 1.5 .9 6. 6 2. 3 11.3 2.9 Saltcedar in Malaga Bend area, New Mexico, Pecos River. 

17 23.9 . 8 . 3 4.1 3. 0 8.2 1.4 Saltcedar in Malaga Bend area, New Mexico, 150 yds downstream from No. 16. 

18 26.3 2. 3 1.1 8. 7 1.0 13.1 8. 7 Saltcedar on Delaware River at U.S. Highway 285 bridge, south of Malaga, N.Mex. 

D.-Vegetation in Rio Grande basin, N.Mex., sampled December 1944 

19 9. 4 1.7 0.5 4. 3 1.4 7.9 3.1 Saltcedar beside interior drain, San Acacia, N. Mex. Leaves brown from recent frost. 

20 13.5 .8 .6 3.6 1.3 6.3 2. 8 Saltcedar beside interior drain, San Acacia, N. Mex. Leaves still green. 21 22.8 .9 .7 5.3 2. 0 8.9 2.6 Saltcedar on old U.S. Highway 85 in Bosque del Apache Wildlife Range near San 

Antonio, N. Mex. 

22 18.6 . 8 . 2 2. 7 1.3 5. 0 2.1 Saltcedar in arroyo 1}.2 miles south of Truth or Consequences, N.Mex. 

23 16.3 1.1 . 3 2.9 1.4 5. 7 2.1 Saltcedar by road 20 yd below No. 22, 1}.2 miles south of Truth or Consequences. 

E.-Vegetation growini where permanent water table is very deep, sampled December 1944 

241 25 11.81 15.1 

0. 61 0. 61 2. 21 0. 51 3. 91 4. 41 Lone saltcedar in highway borrow pit, 5 miles west of Hatch, N. Mex . • 8 . 4 2. 6 . 7 4. 5 3. 7 Lone saltcedar tree by New Mexico Highway 26,5 miles east of Florida, N.Mex. 

F.-Vegetation In Safford Valley, Ariz., sampled Dec:ember 1944 

26 25.7 1.9 1.1 6. 5 2.6 12.1 2. 5 Saltcedar beside Gila River at Solomon ford crossing, Solomon, Ariz. 

27 22.3 1.5 .8 4. 4 2. 8 9. 5 1.6 Saltcedar growing beneath U.S. Highway 70 bridge over San Simon Creek near Solomon, Ariz. 28 26.4 1.6 .6 6.5 5. 0 13.7 1. 3 Saltcedar growing beneath Safford, Ariz., bridge over Gila River; leaves brown from 

frost. 29 14.8 .6 .6 2. 7 2. 2 6.1 1.2 Green saltcedar sprouts on trees in Safford experiment plot, Arizona, at Safford 

30 27.4 1. 8 .7 5.2 bridge. 5.1 12.8 1.0 Green leaves on saltcedar growing beneath Safford, Ariz., bridge. 
C4 STUDIES OF EVAPOTRANSPIRATION 

Several times during the growing season of 1945, 

samples of foilage were obtained from saltcedars along 

the Pecos River inN ew Mexico and examined by a technique designed to determine only the saline material 

present on the outer surfaces of the leaves and stems. 

The collected samples were air dried, and solutes were 

washed from a weighed portion by pouring 125 ml of 

distilled water over the sample supported on filter 

paper in a large funnel. This filtrate was poured 

through the sample twice more and was then increased 

to a definite volume and analyzed. The analytical results are given in table 2. The sodium and potassium 

content was calculated from the difference between determined cations and anions. Very little organic matter 

was present in these solutions. 

The chemical analyses also were computed where 

possible as percentages of the total weight of dissolved 

ions. This could be done only for the analyses which 

included all the major ions. Chemical analyses believed 

to represent the percentage composition of solutes in 

ground water in the vicinity of the plants are included 

in table 2. 

The most mobile solute ions circulated by the plants 

are those dissolved in condensed water or guttation, or 

present as crystalline material on the leaf surfaces. The 

composition of solutions actually present on the leaves 

was determined on one occasion only. During studies 

of the use of water by bottom-land vegetation (described by Gatewood and others, 1950) , it was often 

noticed that at night, during the growing season, 

branches of the thriving stands of saltcedar along the 

river were very wet with highly saline liquid. This 

effect was attributed to guttation, in the absence of complete explanation as to why the water was so saline. 

The diurnal range of air temperature and relative humidity was often wide. The temperature commonly 

dropped from an afternoon high in excess of 100°F to 

nighttime temperatures of 50° to 60°F, and the relative 

humidity at night often exceeded 90 percent. Whether 

guttation was a significant factor, however, is not a 

matter of particular concern here. The important fact 

is that the plants do exude saline material in considerable quantity. 

The approximate com position of the liquid was determined by shaking the branches of a number of 

saltcedars near the Glenbar Experiment Station in the 

early morning of October 18, 1944, over a large shallow 

enamelware pan, to get a sample large enough for 

analysis. The composition of the shallow ground water 

in the vicinity was known from samples collected in 

the past from driven wells (Gatewood and others, 1950, 

p. 81). In table 3, the analyses of water shaken from 

the plants and of water pumped from a nearby shallow 

well are given. 

TABLE 2.-0ompos-it-ion of solids washed from sa"Ctcedar leaves, few minutes contact time, and of solids dissolved in nearby water 

[For tree samples, values in first column under each date are percent of air-dried foliage, and values in second column under each date are percent of determined constituents; 

for water samples, values are percent of determined constituents] 

Tree at Pecos River bridge at Frazier, N.Mex. Pecos River near Acme, 

N.Mex. 

May 24, 1945 July 10, 1945 October 22, 1945 June 1-10, 1945 

Specific conductance, in micromhos at 25°C __ -------- Foliage dry weight ____________________________ grams __ 591 

17.6 

Calcium __ -------------------------------------------- 0. 06 

Magnesium_------------------------------------------ • 02 

Sodium and potassium _____ -------------------------- • 07 

Bicarbonate_-------------------------------__________ . 02 Sulfate ____ ------______________________________________ . 27 

Chloride _____ ------------------- __ ----------------____ . 06 

Sulfate: chloride __ -------------------------- __ -------- ___ --------------

11.6 

3.5 

15.1 

3.5 

54.7 

11.6 

4. 7 

Sum of determined constituents ____ ------------ . 50 ----------------

492 

10.7 

0.13 

.02 

.06 

.03 

.37 

.08 

18.9 

2. 7 8.1 

4.1 

54.1 

12.2 

4.4 

. 69 ----------------

306 

12.9 

0.06 

.02 

.02 

.02 

.14 

.08 

18.6 

4. 7 

7. 0 4. 7 41.9 

23.3 

1.8 

7, 720 

13.7 

3. 7 13.7 

2.3 

43.5 

22.2 

2. 0 

. 34 ---------------- ----------------

Tree at Pecos River bridge near Artesia, N. Mex. Pecos River 

1-------~-------,----------:--------l near Artesia, 

April 4, 1945 May 24, 1945 

Specific conductance, in micromhos at 25°C __________ _ 757 

31.7 

416 Foliage dry weight_ ___________________________ grams __ 7. 0 

Calcium______________________________________________ o. 03 10.8 0. 07 

Magnesium____________________________________________ • 01 4. 3 . 03 

Sodium and potassium________________________________ . 05 18.3 .17 

Bicarbonate ___________________________________________ ------------ ------------ . 03 

Sulfate------------------------------------------------ . 08 28. 0 • 27 

Chloride---------------------------------------------- .11 38.7 . 26 

Sulfate: chloride--------------------------------------- ------------ . 72 ------------

8.6 

3.4 

20.7 

3.4 

32.8 

31.0 

1.1 

Sum of determined constituents ________________ _ • 29 ------------ . 83 ------------

July 10, 1945 

356 

9.0 

0.07 11.3 . 01 1.9 

.11 18.9 

.03 5. 7 .24 41.5 

.12 20.8 

------------ 2. 0 

• 59 ------------

October 25, 1945 

1,140 

10.0 

0.10 6.4 

.02 1.3 

.45 28.2 

.03 1.9 

.28 17.9 

.69 44.2 

------------ .41 

N.Mex. 

August 11-13, 

17-21, 1945 

14,900 

7.4 

3.1 

23.4 

.8 

28.1 

37.0 • 76 

1. 57 ------------ ----------------
COMPOSITION OF SALINE RESIDUES ON LEAVES AND STEMS OF SALTCEDAR C5 

TABLE 2.-0ompositian of soUclB washed from saltcedar leQ!Ves, few minutes contact time, and of soZids dissolved in nearby waterContinued 

Tree at Pecos River at Major Johnson Springs, N.Mex. 

Specific conductance in micromhos at 25°C ____________ _ Foliage dry weight ____________________________ grams __ 

April4, 1945 

1,480 22.3 

Calcium_--------------------------------------------- o. 15 16. 5 Magnesium____________________________________________ . 05 6. 0 

~1~~~~;!-~~~~~~~================================ Sulfate________________________________________________ --------~~- . 44 -------~~~-- 49. 5 Chloride______________________________________________ .19 21. o Sulfate: chloride ______________________________________ ------------ 2. 4 

Sum of determined constituents ________________ _ .89 

May 24,1945 

1, 560 

12.1 

0.33 15.4 .10 4.6 .21 9. 7 .05 2.3 1.12 52.5 .33 15.4 

------------ 3.4 

2.14 ------------

July 10, 1945 October 25, 1945 

525 676 11.1 11.2 

0.11 14.6 0.12 13.0 .04 4.9 .04 5. 0 

.07 9.8 .12 13.0 .05 7.3 .06 7. 0 .36 48.8 .29 32.0 .11 14.6 .27 30.0 

------------ 3.3 ------------ 1.1 

• 74 ------------ .90 

Tree near well 5, Malaga Bend area near Malaga, N. Mex. 

Specific conductance, in micromhos at 25°C ___________ _ Foliage dry weight_ ___________________________ grams __ 

April5, 1945 

1,320 26.7 

May 25, 1945 

3,230 10.3 

Calcium_______________________________________________ 0. 03 4. 7 0. 09 Magnesium____________________________________________ . 01 1. 7 . 03 

~1~~~;!-~~~~~~~================================ Sulfate------------------------------------------------ --------~~~- . 12 ------=~~~-- 18.6 1: . 52 ~ Chloride __ -------------------------------------------- . 29 45.3 1. 62 Sulfate: chloride______________________________________ ____________ • 41 ___________ _ 

2. 7 

.9 

33.3 

.9 

15.2 

47.0 

.32 

Sum of determined constituents ________________ _ .64 3.44 ------------

July 11, 1945 October 24, 1945 

1,360 3,570 16.1 16.3 

0. 02 2.2 0.06 2. 0 .01 1.1 .02 .6 .38 33.9 1.04 34.2 .02 1.7 .07 2.4 .12 11.1 .49 16.1 .56 50.0 1. 36 44.7 

------------ .22 ------------ .36 

1.12 ------------ 3.05 

Tree on terrace near well131, Malaga Bend area near Malaga, N. Mex. 

Specific conductance, in micromhos at 25°C __________ _ Foliage dry weight ____________________________ grams __ 

April 5, 1945 

349 

17.5 

Calcium______________________________________________ 0. 03 11.6 Magnesium____________________________________________ • 01 4. 7 

~~~~~~~-~~~~~~================================ Sulfate________________________________________________ --------~~- .13 ------~~~~-- 51.2 

Chloride __ -------------------------------------------- • 05 18.6 Sulfate: chloride--------------------------------------- ------------ 2. 8 

Sum of determined constituents ________________ _ • 25 ------------

May 25, 1945 

873 

11.4 

0.10 8.4 .03 2.3 .25 21.4 

.04 3.1 .55 48.1 .19 16.8 

------------ 2.9 

1.15 ------------

July 11, 1945 October 24, 1945 

179 450 8.8 U.1 

0. 02 7.1 0.04 6. 0 

.01 1.8 .01 1.5 .07 21.4 .16 26.9 

.02 7.1 .02 3. 0 .16 50.0 .17 28.4 

.03 10.7 .21 34.3 

------------ 4. 7 ------------ .83 

. 32 ------------ .60 

Tree at Delaware River bridge on U.S. Highway 285 near New Mexico-Texas State line 

Specific conductance, in micromhos at 25°C __________ _ Foliage dry weight ____________________________ grams __ 

April5, 1945 

303 

22.6 

May 24, 1945 

568 

14.5 

Calcium ___ ------------------------------------------- o. 02 11. 4 0. 08 Magnesium____________________________________________ . 01 5. 7 • 03 Sodium and potassium________________________________ • 02 14.3 • 06 Bicarbonate ___________________________________________ ------------ ------------ • 02 

Sulfate------------------------------------------------ • 06 40. o • 28 Chloride __ -------------------------------------------- • 04 28.6 .10 Sulfate: chloride--------------------------------------- ------------ 1. 4 ------------

July 11, 1945 

362 

7.3 

14.5 0.05 4.8 .03 10.8 .18 

3.6 .03 48.2 .33 18.1 .19 2. 7 ------------

October 24, 1945 

290 

11.1 

6.8 0.05 12.5 3.4 .01 2.5 22.0 .06 17.5 3.4 .02 5. 0 40.7 .11 30.0 23.7 .12 32.5 1. 7 ------------ .92 

Spring at Major Johnson Springs area 

July 6, 1940 

5,230 

15.0 

3.4 

12.1 

2.9 

44.2 

20.7 

2.1 

Well 5, Malaga Bend 

March 25, 1938 

44,000. 

1.5 

1.2 

34.9 

.4 

9.8 

52.2 

.19 

Well131, 

Malaga Bend 

0 ctober 18, 1938 

9,840 

11.6 

4.0 

17.2 

1.7 

33.7 

31.9 

1.1 

Delaware 

River at U.S. Highway 285 bridge 

July 11, 1945 

2,910 

22.4 

2.1 

4.1 

3.9 

62.3 

3.6 

17.3 

Sum of determined constituents----------------- .15 ------------ • 57 ------------ • 81 ------------ • 36 ------------ ----------------
C6 STUDIES OF EVAPOTRANSPIRATION 

TABLE 3.-M iscellaneous analyses of water associated with 

saltcedar 

[Values are percent of determined constituents] 

.! ~ Calcium ___________________ - _______ - __ -- __ 2.3 7.5 ~agnesium ______________________________ _ . 8 2.1 

Sodium and potassium ____________________ _ 33.6 23.1 

Bicarbonate ______________________________ _ .0 21.8 Suliate __________________________________ _ 19.0 14.0 

Chloride ______________ ---_---------------- 44.3 31.5 

Suliate: chloride _______ -- __ --_-- __ --------- .43 .44 

Specific conductance, in micromhos at 25°C __ _ 55,500 3,260 

1. Water accumulated on saltcedar foliage near Glen bar, Ariz., during night preceding 

Oct. 18, 1944. 

2. Water from wellll-14 near Glenbar, Ariz., Aug. 30, 1943. 

INTERPRETATION OF RESULTS 

The analytical data should be capable of providing information bearing on the following three questions : 

1. How much and what kinds of solutes are present in 

and on saltcedar leaves~ 

2. What relation does the amount and nature of solutes 

in the leaves have to the chemical quality of ground 

water in the vicinity of the plant~ 

3. What effects do other environmental or internal factors have on the composition of solutes in the 

leaves 1 

NATURE AND AMOUNT OF SOLUTES 

The amount and composition of material leached 

from the saltcedar leaves obviously are functions both 

of the amounts present on the leaf surfaces or within the 

plant tissues and of the effectiveness of the method used 

to bring them into solution. The rather rigorous leaching used for samples listed in table 1 probably explains 

the fact that this procedure gave soluble contents from 

9.4 percent to more than 30 percent of the dry-foliage 

weight. The simple washing of leaves used for samples 

listed in table 2 gave soluble contents ranging from a 

few tenths of a percent to a little over 3 percent, or about 

a tenth as much as the leaching treatment. The analysis in table 3 of the moisture naturally appearing on 

the leaves is obviously influenced by many extraneous 

factors and cannot be related to leaf weight or area. The 

solutes in this water are the most transient part, being 

subject to rapid removal by wind action. 

The methods used to obtain the data in table 2 give 

results that are indicative of the amounts of soluble salt 

which might be washed from saltcedars by rainfall during the growing season. The more rigorous leaching 

procedure used for samples in table 1, however, probably 

approximates the total amount of the determined ions 

which can be extracted from leaves which fall to the soil 

surface and decompose. 

The sodium content of the leaf extracts in table 1 was 

not determined; and because of the large amount of organic matter in the solutions, a meaningful value cannot 

be calculated from the ion balance. Therefore, ion percentages cannot be calculated for these data. The ratio 

of sulfate to chloride reported for the analysis, however, 

does have some usefulness in comparing data in table 1 

with that in table 2. 

The sum of inorganic ions reported in table 1 is generally no more than half the total soluble residue. Although sodium was not determined, it could account for 

only a small part of this difference. No significant concentrations of bicarbonate were found in those extracts 

which were analyzed for this constituent. For most 

samples, the four ions determined comprised from 5 to 

15 percent of the dry weight of the leaves. 

Although one might casually expect the inorganic 

solutes extracted from saltcedar leaves to be mostly 

sodium and chloride, the results of the leaching and 

washing experiments show that sulfate is generally the 

predominant anion. Surficial moisture from the leaves, 

however, may contain principally sodium and chloride 

as indicated by the single analysis of this material in 

table 3. It seems probable that sulfate is held to a 

greater extent within the leaf structure, and chloride to 

a greater extent is transported to the outer surface of 

the leaf from which it can be periodically removed by 

wind and rain. This inference is supported by the generally higher sulfate to chloride ratio for the more intensively leached samples (table 1) than for those simply washed with distilled water (table 2). 

RELATION OF LEACHED SOLUTES TO GROUNDWATER QUALITY 

The kinds and amounts of inorganic solutes on the surfaces of saltcedar leaves, as well as the amount present 

within the leaf structures and available for leaching, are 

influenced by numerous variables. In a general way, 

one would expect the composition of the leachings to be 

related to that of the water available to the plant roots, 

modified by whatever selective processes the plant might 

be able to exercise to absorb or reject certain solute ions. 

The composition observed would then be further modified by such factors in the sampled part of the plant as 

the rate at which water has been transpired and the rate 

of metabolic processes. More external but still important factors affecting the composition of leachings might 

include the length of time which has passed since the last 

rain or windstorm, the season of the year, and the manner in which the leaves for sampling are selected. 

It probably is not surprising that very little can be 

deducted from the data in tables 1 to 3 to indicate the 

effect of the composition of the water supply. In many 

places, the composition of the water available to the 
COMPOSITION OF SALINE RESIDUES ON LEAVES AND STEMS OF SALTCEDAR 

plants, from which leaf samples were taken, is very imperfectly known. In table 2 an analysis of ground 

water or of low-flow water from the adjacent stream 

is included for each sample location. Somewhat similar 

information is available (Hem, 1950) for some of the 

sampling sites in Safford Valley. The actual composition of moisture available to plant roots may differ 

somewhat from the ground-water composition in the 

vicinity; however, until more is known about root-zone 

behavior of solutes, it is useless to speculate about this 

question. 

Gross differences in ground-water composition do 

seem to be reflected to some extent in the composition of 

the extracts in table 1. Sam pie 7 was obtained from a 

saltcedar growing along a drainage ditch which had apparently been used for some years to convey the unused 

salty water from a small flowing well to a nearby wash 

channel. The chloride concentration of this water was 

6,800 ppm (parts per million), and its dissolved solids 

were 14,000 ppm. The percentage of chloride in the leaf 

sample was higher than for most others in table 1, which 

represented for the most part trees having a less saline 

water supply. Samples 10 and 11, also having high 

chloride percentages, came from trees growing near 

Fort Thomas, .Ariz., in an area where the ground water 

probably had between 3,000 and 4,000 ppm of chloride. 

The remaining two samples (Nos. 28 and 30) which 

showed very high chloride contents were from trees 

growing under a bridge, where the leaves were protected 

from rain, and therefore they are not really comparable 

to the others. 

The total percentages of inorganic ions reported in 

table 1, although not including sodium, do seem to have 

a systematic trend. The highest totals generally are 

found in group C, which represents trees growing in the 

Pecos River basin. The dissolved -solids concentration 

of ground water available to the plants probably was 

considerably higher in that area than in the Rio Grande 

basin. The lower total ion contents of the leaves in 

group D are in accord with this interpretation. 

Table 2 also shows some effects related to composition 

of the water supply. The tree growing near well 5 in 

the Malaga Bend area where the shallow ground water 

is very saline gave consistently higher chloride percentages in the leaves than did trees at other locations. 

It also had a sulfate to chloride ratio below 1.0 consistently through the growing season. 

The sulfate to chloride ratio of the surficial moisture 

from saltcedar leaves (table 3) is nearly the same as 

that of ground water in the vicinity. .Although this 

may be fortuitous, the ratio for leaf samples from 

nearby trees (table 1, sample 6) is much higher and 

suggests the sulfate is mostly present within the leaves. 

EFFECTS OF OTHER FACTORS 

Several analyses in table 1 give some indication that 

the younger, more vigorously growing leaves contain 

somewhat larger proportions of chloride than do 

mature leaves. Pairs of analyses showing this effect 

are those for samples 8 and 9 and samples 10 and 11. 

The first in each pair represents new growth and has a 

significantly lower sulfate to chloride ratio than the 

second, which represents mature growth. 

The successive samples in table 2 give some general 

indications of effects of rainfall and passage of time 

during the growing season. A major factor affecting 

the results is the transfer of loose salt deposits from leaf 

surfaces to air or ground by wind movement, by rain, 

or by the drip of moisture accumulated on the plant 

leaves in other ways. Surficial deposits of sodium 

chloride, being loosely attached and readily soluble, 

probably are rather easily removed by wind and by 

dripping of condensed moisture or guttation. 8alt 

exuded from salt glands in the form of so-called 

whiskers (Decker, 1961) would readily become airborne. Even in the absence of heavy rain, therefore, it 

might be expected that total con~ent of soluble ions and 

the sulfate to chloride ratio would tend to increase with 

time. 

The effect of rainfall is evident in some of the analyses. A moderate to heavy shower should remove all 

readily soluble material from the leaf surfaces; if some 

of this intercepted rainfall actually enters the plant directly, as may happen, the solution within the leaf 

tisues may be diluted somewhat. In any event, several 

days might have to pass after the rain before a normal 

deposit of saline material would again build up on the 

leaf surfaces. Leaves collected soon after a rain should 

contain a lower percentage of solute ions than leaves 

which had not been rained upon for some weeks. 

Samples of leaves obtained July 10 and 11,1945, from 

the locations at and downstream from .Artesia, N. Mex. 

(table 2), were influenced by a general rainstorm which 

had occurred in that area a few days before. For all 

the sites where rain had occurred, the percentage of 

solute ions in the leaves obtained in July was lower than 

at the previous sampling. Very little precipitation occurred in the Pecos basin during the months of April, 

May, and June of 1945. 

Figure 1 shows the average ratio of sulfate to chloride 

for each of the four sets of samples obtained during the 

growing season of 1945 (table 2) . The general trend 

in the ratio was upward until after the July sampling. 

In common with other properties related to the plantgrowth pattern, this ratio and the soluble percentage of 

the dry weight of the leaves would both be expected to 

increase most rapidly during the period of ·highest 
C8 STUDIES OF EVAPOTRANSPIRATION 

5.0 

(1944) 

-------() 

-- ---- --- 4.0 

--

--~ 

~:::::-:= __ ------r-_ 

----....... ......... 

v "" \ 

\ 

\ 

/ \ 

\ 

/I \ 

\ 

I 

I 

3.0 

o-tj_ 

(/) (,) 

2.0 

/ I 

/ 0 1.0 

0 

Mar. Apr. May June July Aug. Sept. Oct. Nov. 

1945 

FIGURE 1.-Average sulfate to chloride ratio in solutes washed from saltcedar leaves, Pecos River basin, N. Mex. Heavy rainfall preceding 

October 1945 sampling probably caused an abnormally low sulfate :chloride ratlo. 

growth rate and to level off later in the growing season 

when growth rates are lower. The last sampling, however, which was made in late October, showed a very 

pronounced decrease in the ratio, to a little under 1.0. 

Precipitation in the Carlsbad-Artesia area in October 

1945 was unusually heavy and probably accounted for 

the ratio decrease. From this rather fragmentary infurmation, one cannot be certain that the decrease was 

the result of rainfall, but the average ratio of sulfate to 

chloride for samples obtained in November 1944 in the 

Pecos River basin (table 1) was a little over 4.0. The 

data probably are not completely comparable, but the 

general seasonal trend and the effect of rainfall would 

be interesting subjects for further study. 

In table 1, there are two samples of leaves obtained 

from trees growing under the county highway bridge 

across the Gila River at Safford, Ariz. The trees in 

this location were protected from rain, although they 

were probably still losing salt from their leaves in other 

ways. Both samples 28 and 30 contained at least 5.0 

percent of chloride and thus had the highest concentrations observed in any of the samples represented in 

the table. 

CONCLUSIONS 

The total inorganic solute content of saltcedar leaves 

and deciduous stems may exceed 15 percent of the air-dry 

weight. The predominant anion in the analyzed samples was generally sulfate, although chloride was also 

abundant and was the predominant anion in a few. The 

composition of total solute content of leaves was not 

closely related to composition of the ground water in the 

area where the plants were growing. It seems likely, 

however, that chloride must be strongly predominant 

in the water available to a plant to maintain a value 

below 1.0 for the sulfate to chloride ratio in the leaves. 

The solutes which can be washed from the leaves by 

fairly brief contact with water, as during a rainstorm, 

constitute as much as 3.5 percent of the dry weight of 

:foliage of plants growing where the water supply is high 

in dissolved solids. Where the available water is lower 

in dissolved solids, the solute content of the leaves is 

lower. More rigorous leaching may bring into solution 

as much as 30 percent of the dry weight of foliage, but 

a considerable part of the dissolved material is organic. 

As the growing season advances, inorganic solutes 

tend to accumulate in and on the leaves. This trend may 

be interrupted or reversed by rainfall that is sufficiently 

heavy or prolonged to wash away some of the accumulated material. The available data suggest that the ratio 

of sulfate to chloride in the leaves usually tends to increase during the growing season. Except where the 

ground water in the vicinity was very high in chloride, 
COMPOSITION OF SALINE RESIDUES ON LEAVES AND STEMS OF SALTCEDAR C9 

the solute washed from the leaves contained more sulfate than chloride. 

Moisture which collected on saltcedar leaves at night 

along the Gila River near Glenbar, Ariz., was strongly 

saline and contained mostly sodium and chloride. The 

cubic crystals, apparently sodium chloride, which occur 

on saltcedar leaves, are probably deposited when such 

saline solutions evaporate. 

The chloride ion content of the solutes present in saltcedar leaves is probably affected more than the sulfate 

content by various processes that may remove salty 

fluids and dry salt crystals from the leaves. 

Samples were obtained from trees growing in widely 

separated areas, and the composition of ground water 

available to them had a wide range. The range of composition of the solutes leached from the leaves, however, 

was narrower than the range of associated ground-water 

composition. One may thus conclude that selective 

processes within the plant strongly influence the composition of solutes which can be leached from the leaves. 

Obviously the data presented here do no more than 

suggest some general tendencies in the movement of 

inorganic solutes from the ground water and soil moisture through the saltcedar plant. More detailed studies 

in which the environmental variables are more closely; 

observed and can be controlled are needed before more 

firm conclusions can be reached. 

LITERATURE CITED 

Anderson, M.S., Lakin, H. W., Beeson, K. C., Smith, F. F., and 

Thacker, Edward, 1961, Selenium in agriculture: U.S. Dept. 

of Agriculture, Agr. Research Service, Agriculture Han db. 

200, 65 p. 

Campbell, C. J., and Strong, J. E., 1964, Salt gland anatomy in 

Tamaria; pentandra (Tamaricaceae): The Southwestern 

Naturalist, v. 9, p. 232-238. 

Decker, J. P., 1961, Salt secretion by Tamaria; pentandra Pall.: 

Forest Sci., v. 7, p. 214-217. 

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, Ariz.: U.S. Geol. Survey WaterSupply Paper 1103,210 p. 

Hem, J. D., 1950, Quality of water of the Gila River Basin above 

Coolidge Dam, Arizona: U.S. Geol. Survey Water-Supply 

Paper 1104, 230 p. 

Robinson, T. W., 1965, Introduction, spread, and areal extent of 

saltcedar (Tamarix) in the Western United States: U.S. 

Geol. Survey Prof. Paper 491-A, p. Al-A12. 

Sutcliffe, J. F., 1962, Mineral salts absorption in plants: London, 

Pergamon Press, 194 p. 

U.S. GOVERNMENT PRINTING OFFICE: 1117