382 LEOUMIXOSAE 



Aloug the lower Colorado River we measured a number of largo trees of this species in 1912. 

 At Ehrenberg, Ariz., an individual 20 feet higli and 35 feet in crown diameter, had a trunk 14 

 inches in diameter at 3^{> feet. In the lower Palo Verde Valley an individual 31 feet high and 

 26 feet in crown diameter was 14 inches in trunk diameter at 2 feet. In the region of Milpitas, 

 eastern Colorado Desert, the mesas sloping up from the river sometimes bear remarkable wood- 

 lands of Olueya tesota and Cercidium torreyanum. Near Milpitas a tree of Olneya tesota 46 

 feet high had a trunk diameter of 32 inches at 1 foot, the smallest part of the 4 foot trunk. 

 Another individual, 32 feet high and with a crown diameter of 47 feet, had a trunk diameter of 

 26% inches. 



The flowers, produced mostly on the upper part of the cro\vn, appear in May, after which the 

 old leaves fall and the new leaves come. The very hard and heavj' wood is used by the desert 

 Indians for arrow parts and tool liandk'S. 



Locs. — Yaqui Well, e. San Diego Co., Jcpson 8790; Pilot Knob, se. Colorado Desert, Jepson; 

 Shavers Well near Mecca, Jepson; Coachella, Clary; Chuckwalla Range; Riverside Mts., e. River- 

 side Co., Jepson 5243 ; Whipple Mts., along Colorado River, Jepson 5223. 



Refs. — Olneya tesota Gray, Mem. Am. Acad. n. s. 5:328 (1855), type loc. tablelands of 

 the Gila River, Ariz., Thurher, Gray; Torr. Pac. R. Rep. 7': 10, pi. 5 (1856). Jepson, Silva Cal., 

 261 (1910), Man. 580, fig. 573 (1925). 



26. SESBANIA Scop. 



Herbs or shrubs with pinnate leaves and numerous entire leaflets. Flowers 

 commonly yellow, 1 to several on slender axillary peduncles. Calyx broadly cam- 

 panulate with 2 deciduous bractlets at base. Banner circular or oval; wings ob- 

 long; keel blunt. Stamens diadelphous (9 and 1). Ovary mostly stipitate, many- 

 ovuled. Fruit elongated-linear, partitioned between the seeds. — Species about 40, 

 warm regions of both hemispheres. (Sesban, Arabic name of one of the species.) 



1. S. macrocarpa Muhl. Colorado River Hemp. Annual, 3 to 10 feet high; 

 leaves exceeding the flowers; leaflets 13 to 41 pairs, narrowly oblong to linear, mu- 

 cronulate, 5 to 14 lines long; calyx-teeth short, acute, salient; corolla yellowish, 

 brownish-mottled, 6 to 7^2 lines long; pods 4 to 9 inches long, 1 to 2V3 lines wide. 



Overflowed lands, 5 to 200 feet: lower Colorado River and Colorado Desert. 

 East to Virginia and Florida, south to Mexico. Sept.-Nov. 



The plants of the Arizona-Sonora region have been separated (as Sesban sonorae Rydb.) 

 from those of the Mississippi region (S. exaltatus Rydb.), but we find, by careful scrutiny of a 

 long scries, that the presumed differences (merely those of degree) disappear. Specimens from 

 Culiacan, Sinaloa, Mex. (T. Brandegee), show as many as 82 leaflets (not merely "16-30"), 45 

 seeds to the pod (not merely "15-30"), while the calyx -lobes are no more "subulate" than in 

 some specimens of the Mississippi Valley. Other western specimens fortify this argument. 



Econ, note. — Along the lower Colorado River the plant is very abundant, developing on the 

 bottom lands in June after the fall of the spring floods in the river. It is a fiber plant producing 

 smooth, lustrous, and very strong white filaments which are used by the Yuma Indians for nets 

 and fish-lines. In the Palo Verde Valley the seeds are used by the settlers for chicken feed. This 

 species is, too, as we learn from I. T. Weeks, used in cultivation in the Imperial Valley as a 

 cover plant to shade watermelons and as a soil builder in grape-fruit orchards. 



Locs. — Palo Verde Valley, Jepson 5257; Imperial, Parish 8309; Cameron Lake, Colorado 

 Desert, T. Brandegee ; Calexico, Davy 8015; Yuma, W. II. Eolahird. 



Refs. — Sesbania macrocarpa Muhl.; Raf. M. Ludov. 137 (1817), type loc. New Orleans, 

 La.; Jepson, Man. 580, fig. 574 (1925). Darwinia exaltata Raf. Fl. Ludov. 106 (1817). Sesban 

 exaltatus Rydb. X. Am. Fl. 24:204 (1924). Seshania macrocarpa var. picta Wats. Proc. Am. 

 Acad. 24:46 (1889), type loc. Guaymas, Sonora, Palmer. Sesban sonorae Rydb. N. Am. Fl. 

 24:205 (1924), based on last. Sesban macrocarpa Sta. Contrib. U. S. Nat. Herb. 23:477 (1922), 



27. VICIAL. Vetch. Tare 



Annual or perennial herbs with weak angular stems, often slightly climbing. 

 Leaves pinnate, with several to many leaflets and semi-sagittate stipules, the rachis 

 ending in a simple or branched tendril. Flowers solitary or racemose, axillary, the 

 racemes one-sided. Cal;y^ 5-toothed, the three lower teeth often longer. Banner 

 oblong, or appearing so by the turning back of the edges; wings united to the middle 

 of the keel. Stamens diadelphous (9 and 1) or monadelphous below. Style fili- 



