PEA FAMILY 



241 



at Barstow, this species with its dark foliage, produced in June, forms a grateful thread of green 

 in the river bottom. In the Colorado River bottoms between Needles and Yuma it is more abun- 

 dant than elsewhere in California. Just as in the case of other trees of "bottom" lands it suffers 

 from floods. Like the Honey Mesquite, however, the cables in its root system are often 10 to 30 

 feet in length and serve well for anchorage. We watched the flood of January 17, 1916, come 

 down the Mohave Eiver from the San Bernardino Mountains into the desert. The waves some- 

 times ran as high as flve feet from trough to crest; and, though Screw-bean thickets lay in the 

 path of the heaviest currents, comparatively few trees were taken out of the river bottoms. 



In the desert, miners and prospectors collect the pods of the Screw-bean Mesquite as a winter 

 store, brown or roast them in an oven, grind them rather fine and use for the preparation of 

 a beverage. These beans are regarded as an excellent substitute for coffee and the dtesert men are 

 fond of the Screw-bean drink. The spikes set from 1 or 2 to 15 fruits. 



Locs. — Panamint Valley (Contrib. U. S. Nat. Herb. 4:90) ; Furnace Creek, Funeral Mts., 

 Jepson 6934; Tecopa, Jepson; Barstow, Jepson 4806, 6591, 6592; Colorado River, opp. Parker, 



Jepson 5233; Riverside Mts., Colorado River, Jepson; 

 Palo Verde Valley, Jepson. 



Refs. — Peosopis pubescens Benth.; Hook. Lond. 

 Jour. Bot. 5:82 (1846), type loc. stated as "California 

 between San Miguel and Monterey," Coulter, but un- 

 doubtedly collected far southeastward as were various of 

 Coulter's spms. attributed to coastal Cal. ; Jepson, Man. 

 514, fig. 514 (1925). 



5. CASSIA L. Senna 



Herbs or shrubs with even-pinnate leaves. 

 Flowers (in ours) yellow, in racemes. Sepals 5, 

 distinct or nearly so. Corolla regular, with 

 spreading petals. Fertile stamens (in ours) 7, 

 the anthers opening by 2 pores at the apex, the 3 

 remaining stamens represented by short sterile 

 filaments on the upper side of the flower. Pod 

 usually curved, many-seeded. — Species 450, 

 warmer regions, all continents except Europe. 

 (Ancient Greek name.) 



Herbage glabrous or nearly so ; stipules and stipels none ; 



racemes terminal _ 1. C. armata. 



Herbage finely and densely white-pubescent ; stipules and 



stipels filiform ; racemes axillary 2. C. covesii. 



1. C. armata Wats. (Fig. 175.) Much- 

 branched bush 2 to 4 feet high; shoots of the sea- 

 son thickish, green, almost leafless, ending in ra- 

 cemes 3 to 7 inches long; leaf-rachis elongated, 

 dilated, ending in a conspicuous point, bearing 1 

 to 4 pairs of leaflets; leaflets distant, oblong or 

 ovate, 2 to 4 lines long; petals roundish, bright 

 salmon-color, 4 to 6 lines long; pods often curved, 

 1 to 1% inches long. 



Sandy washes in the desert, 500 to 2000 feet : 

 Colorado and Mohave deserts and north to Inyo 

 Co. East to Nevada and western Arizona. May- 

 June. 



Field note. — The shoots of the season, dying back 

 each summer and commonly bending over to the ground, are 

 replaced the next year by new shoots. The bushes thus 

 become broad — once to twice as broad as high and full of 

 old dead stems which give the heart a black appearance. 

 In the broad shallow washes of the central Mohave Desert the species is often abundant, forming 

 the dominant vegetation. Flowering, in the years of considerable rainfall, is luxuriant. There 



Fig. 175. Cassia armata Wats. 

 a, fl. branchlet, X % ; &, fr., X %. 



