1907] Hall. Compositae of Southern California. 97 



crowded broom-like clumps : leaves few, linear, entire, 2 cm. long 

 (or usually much less), not over 5 mm. wide (those of the branch- 

 lets sparse and much reduced) , 1-nerved : heads mostly solitary on 

 the naked wiry peduncles but these are so numerous that the 

 infllorescence is densely paniculate : involucre campanulate or 

 oblong, barely 5 mm. high, closely imbricated ; outer bracts oval, 

 obtuse, very firm; the inner ones thin, narrow, and much elon- 

 gated: achenes glabrous, 10-nerved: pappus of fertile flowers 

 soft and copious, sordid or reddish, 6 to 8 mm. long; of the 

 staminate flowers scant, slightly dilated at tip but not bearded. 



Southwestern San Diego Co., Arizona, and Mexico : therefore 

 to be expected anywhere along our southern border : plentiful in 

 dry soil from Mission Valley, near San Diego, and the Sweetwater 

 dam to the Mexican line. 



4. B. sergiloides Gray, Bot. Mex. Bound. 83 (1859). 



Erect glabrous shrub, 1 or 2 m. high, with many broom-like 

 branches : twigs green, strongly striate-angled, either nearly leaf- 

 less or the sterile shoots leafy : leaves entire or rarely few-toothed, 

 linear to spatulate or obovate, usually small and sparse but some- 

 times numerous and as much as 4 cm. long by 2 cm. broad on 

 sterile shoots : inflorescence densely paniculate ; heads solitary on 

 the short bractless peduncles: involucre about 5 mm. high, its 

 bracts firm : receptacle either flat or conical, bearing few or nu- 

 merous chaffy bracts among the flowers similar to the inner bracts 

 of the involucre : achenes 10-nerved : pappus rather rigid and 

 scanty, not elongated in age, of the fertile flowers even in fruit 

 not surpassing the style and barely twice the length of the 

 mature achene. 



Lower Sonoran Zone, in dry creek-beds, etc., from the east 

 base of San Jacinto Mt. and San Felipe Creek across the Colorado 

 and Mohave deserts to Nevada and Utah: Banner, San Diego 

 Co., Apr., 1901, Brandegee; Chuckawalla Bench, Riverside Co., 

 Oct. 9, 1904, Scliellenger, no. 6 (nearly leafless) : Providence Mts., 

 May 25, 1902, Brandegee (very leafy). In the Panamint Mts. 

 this species is restricted to the vicinity of the small streams 

 occupying the bottoms of the steep narrow canons, and for this 

 reason is known to miners as the "Desert Willow." 



