The Search for New Industrial Crops IIh Prospectus of Lesquerella fendleri

H O W A R D S C O T T G E N T R Y and A R T H U R S. B A R C L A Y 1

Among wild plants, Lesquerella fendleri (Gray) Wats. of the Cruciferae, is one of the most promising for new crop develop- ment. A recent article (1) reported the commercial potential latent in its oil-bearing seeds and another (2) combined a description of the genus in summary with the oil analy- ses of seventeen species. After the pre- liminary screening of the genus, the wild native stands of L. fendleri were investigated in detail. The following botanical account reports information pertinent to further de- velopment of this species as a new crop prospect.

The Nature of Lesquerella fendleri

Lesquerella fendleri in western Texas is a fall-spring annual. Regional floras (3) and Payson's monograph of the genus (4) treat it exclusively as a perennial. This in- terpretation is doubtless due to the presence of the thick, rather woody, tufted root crown

1U.S.D.A., Agricultural Research Service, Crops Research Division, Beltsville, Maryland.

of the plant as it appears on herbarium specimens collected in the spring or early summer when late rains prolonged the life span. The plants observed in western Texas germinate in late summer and fall, live over winter and flower in the spring. They de- velop strong tap roots ~nd branched root crowns and by spring strongly simulate tufted perennials. Young seedlings have been observed in October and December, a few of the larger with abortive flowers. When seed maturation is complete or when soil moisture fails, the whole plant dries and the taproot easily breaks just below the soil sur- face. Figures 1 and 2, photographed in M~y, show dried plants blown over and about like tumbleweeds, the capsules still intact. The winds and flooding rains disperse the seeds widely.

Lesquerella fendleri varies in many ways. Payson stated (4), it "is certainly the most polymorphic species ill this genus." Popu- lations show different aspects, as early or late seeding, tall or short plants, a general ten- dency to be strictly erect or spreading, etc.

Fig. 1. L. fcndleri, mature dry pl'mt being Fig. 2. Wind-blown and bottom up with the pushed over by the wind. tap root exposed.

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The degree to which environmental factors and genetic composition effect the population differences is obscure. However, individual plants growing in uniform habitats show striking phenotypic differences which prob- ably have a genetic basis. On a single local lens, for instance, and again upon a uniform sandy flat the following individual plant variations were noted.

Plants that bloomed and seeded early, while others were late with flower and seed.

Plants with short blooming period, con- trasting with plants of long blooming period.

Spreading decumbent habit or strict erect habit.

Few-tufted plants as well as prolifically- tufted plants.

Heavy seeders and light seeders. Plants with small capsules or plants with

large capsules. Many of these variants appeared to repre- sent forms, as a small-capsuled, strictly erect, fine-stemmed one that regularly oc- curred in a percentage incidence in a Pecos population. Some individual plant varia- tions are apparent in figures 3 and 4.

The range of variation exhibited by L. fendleri would supply the plant breeder with a wealth of genetic material. I t appears that selection alone could, within a few genera- tions, on varying soil types, produce varie-

ties very suitable to crop culture, amenable to machine harvest, and with relatively high yields.

Environment of Lesquerella fendleri The general distribution of Lesquerella

fendleri is indicated in Figure 5. This area is large,, but site preferences exclude the species from saline soils and other edaphic conditions, as discussed below, and large tracts within the area may be without the plant. This area constitutes a large portion of the North American short-grass prairie or Grama Grassland. Bouteloua, Hilaria and other grasses are common associates, but L. fendleri incidence is low where grassland is at or near its climax. I t prefers the more open sites of bare soil and becomes abundant on the drier sites of grassland where mes- quite and Larrea are the characteristic shrubs. L. fe~dleri pioneers readily on dis- turbed soils, as along highways (Figs. 3, 6).

The climate of Lesquerella fendleri is cool and senti-arid. The hot summers are to be excluded, as the plant at this season is a quiescent seed. Generally, it occupies eleva- tions between 2000 and 6000 feet. Annual average precipitation r.anges from 20 to 16 inches. Although some 75-80% falls during the convectional storms of summer and fall, the lighter more regular winter rains and snows are relatively more effective in main- taining soil moisture. The growth period

Fig. 3. L. fendleri, two late-flowering plants Fig. 4. A luxuriant plant growing on a border snd one early-flowering; near Marathon, Texas. of sandy loam near Pecos in May.

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E C O N 0 2 ~ I I C B O T A N Y

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Fig. 5. The natural area of LesquereUa fendleri ia North America.

appears to be September through April. A study of U.S. weather records (5) shows that mean precipitation for these months for eleven stations in western Texas and ad- jacent New Mexico was as shown in Table 1.

Resident observers in Texas report that the abundance of "Yellow Top" depends upon good late summer and fall rains. When these are lacking, Yellow Top is poor. In- florescence and seed will be light unless win- ter rains follow on through into March.

Winter rains diminish gradually southward and in southern Durango and Zaeatecas com- pose a bare 10% of annual precipitation (6). This may be the factor delimiting the south- ern boundary for L. fendleri.

The above figures indicate that 8 to 10 inches of rain or its equivalent in irrigation, distributed from September to April, would be adequate for growth and seed yield. This approximates the moisture needs for winter grains and of these only oats would perhaps

THE SEARCIt FOR lqE~V INDUSTRIAL CROPS I I I 209

vie with L. fendleri in minimal water re- quirements.

Low winter temperatures may be severe in the Yellow Top area. Below zero F readings have been recorded for many stations (5); viz., Barstow, For t Stockton, Artesia, Carls- bad, Roswell ( - -29) and others. Mean Jan- uary minima r~mge from 21 ~ to 30 ~ F. L. fendleri, therefore, has a strong cold toler- ance or a theoretical qualification for north- ward cultivation. I t also survives the high winds of the plains, prevalent in the spring. While these general climatic conditions indi- cate the broad tolerances of L. fendleri, they do not show its limitations.

The soils of Lesquerella fendleri are cal- careous, sandy and well-drained. Samples of sandy loam from near Pecos have p H values of 8.2 and 8.3. These readings are typical of the caliche soils through the short grass- land area from the Panhandle to Zacatecas. The soil profiles are immature and shallow. Such soils commonly have ample phosphorus, are lacking in nitrates, and may or may not have sufficient potash. The plant is absent on local sites of gypsiferous outcrops and saline soils. I t is also lacking on heavy and poorly drained soils. Flowering plants on flat sandy loam soils near Peeos were found dead and dried in May, apparent ly as a re- sult of standing water supplied by a local rain storm in Apr i l (Fig. 7). Other similar flats nearby, but with a gravel substratum, supported plants that matured seed. On such mesquite flat-lands, the best developed plants were almost invariably found on low mounds or borders (Fig. 3).

Fig. 6. Lesquerella fendleri along highway 90, west of Pecos, Texas. Once cleared, the site is reverting to Larrea.

TABLE 1

PRECIPITATION IN L. fendleri AREA (IN INCHES)

Sept. 1- Ca. % of Annual Station April 30 Total an. average

Barstow 6.75 60 10.64 Buena Vista 8.29 75 12.57 Fort Stockton 7.78 50 15.22 Grand Falls 6.66 60 10.09 Artesia 7.15 70 12.58 Carlsbad 6.60 50 14.07 Roswell 7.26 40 14.09 Fort Davis 7.25 40 17.17 Kent 7.15 70 12.79 Marathon 6.97 40 17.53 Sierra Blanca 3.51[ 40 9.45 Fig. 7. L. fendleri dead in flower on a sandy

flooded flat near Pecos.

210 ECONO3KIC BOTANY

Fig. 8. Harvesting Lesqzlerella fcndleri near Pecos, Texas, May ]961.

The plants occur on sand, but only where caliehe underlies the sand nmntle a few inches. On thick lenses of sand they are lacking. Caliche is the prevailing substratum throughout the L. fendleri area. The species is absent in eastern Texas and so is ealiehe.

Yield Lesquerella fendleri produces seed in

abundance; Figures 1, 3, and 4, show the congested crowns of mature capsules. Each capsule contains from 10 to 26 small seeds, which do not fill the two cells. There are commonly 10 to 15 capsules in each raceme.

Each well developed plant has 40 to 50 racemes and on one exceptionally large indi- vidual approximately 400 racemes were counted. Seed from one heavily seeding plant weighed about 1/2 ounce. Other than such indications, there are no yield data available. The writers ' observations con- vinced them that seed production is out- standing and would perhaps double the yield of flaxseed or exceed 1000 lbs. per acre un- der cultivation.

Seed-holding capacity of the capsule is excellent. All capsules remain intact upon the plant until af ter the whole plant dries

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or until wet by rain. Although the capsules develop from the base of the .,hoot upwards as it elongates, the earliest capsules do not open until the entire shoot has dried. Also early and late flushes of shoots may be har- vested together. However, rain causes the immediate opening of dried capsules and loss of seed. This appears to be a form of hydrostatic dehiscence and would constitute a farming hazard in regions where rains are common in May. Our seed gathering at Pecos in May was, in fact, abrupt ly terminated by local thunder showers. Such storms in May are said to be infrequent there, so that normally there would be a period of two to four weeks of good harvest weather. Seed at Hobbs, New Mexico, was still available in mid-June of 1961.

I t was demonstrated at Pecos that seed can be harvested by machine. An Allis Chalmers 1, 1-man combine with an 8-Ioot cutter bar, was employed in field harvesting several hundred pounds of seed from natural stands (Fig. 8). This proved a successful opera- tion in spite of the relatively rough terrain, spotted with mesquite shrub, and the short, variable plants composing the stands.

Summary

Lesquerella fendleri appears to have many of the prerequisites for cultivation. Among

13~iention of equipment by trade-name im- plies no preference over similar equipment made by other manufacturers.

the more obvious qualifications are its annual nature, erect compact habit, ability to colon- ize disturbed soils, seed productivity and seed-holding capacity, tolerances to drought and cold, and a polymorphic character en- dowing this species with excellent breeding assets. The principal limitation appears to be a requirement of well aerated calcareous soils. Lime appears essential. This all sug- gests that it be drill-seeded, with lime on non-calcareous soils, on small borders in rows about 1 foot apart . The growing sea- son corresponds rather closely with the win- ter grains. Hence, L. fendteri may prove to be a practical replacement crop for grains now being produced in surplus.

Literature Cited

1. Mikolajczak, K. L., Earle, F. R., and Wolff, I . A . Search for New Industrial Oils VI. Seed Oils of the Genus Lesquerella. Journ. Amer. Oil Chem. Soc. In press.

2. Barclay, A. S., Gentry, II. S., and Jones, Q. Search for New Industrial Crops I I : Lesquerella as a Source of New Oilseeds. Econ. Bot. 16: 95-100. 1962.

3. Kearney, T. H., and Peebles, 1t. tI. Flower- ing Plants and Ferns of Arizona. U.S. Dept. Agri. Misc. Publ. 423, 1942.

4. Payson, E. B. Monograph of the Genus Lesquerella. Ann. Mo. Bot. Gard. 8: 103-236, 1922.

5. U.S. Dept. Agri., Weather Bureau. Sum- maries of Climatological Data, Bull. Weather, 2nd Ed. 1, sect 2, 1926.

6. Gentry, tI. S. Los Pastizales de Durango. Inst. Mex. tree. Nat. y l~en. 1957.