GRASS FAMILY 9] 



Spikelets not over 1 line long. 



Sheaths glabrous 8. P. lindlicimeri. 



Sheaths pubescent. 



Plants velvety-pubescent 12. P. thermale. 



Plants more or less pubescent but not velvety. 



Vernal blades glabrous above 10. P. occidentale. 



Vernal blades pubescent above. 



Upper surface of blades pilose; autumnal form decumbent-spreading 



11. P. pacificum. 



Upper surface of blades appressed-pubescent ; autumnal form erect or ascend- 

 ing 9. P. huacliucae. 



A. TRUE PANICUM. Annuals or perennials of various habit, but not forming 

 winter rosettes of leaves different in appearance from the culm leaves, 

 nor presenting a distinct vernal and autumnal aspect. 



1. P. arizonicum Scribn. & Merr. Annual ; culms usually branching from 

 the base, glabrous except below the panicle, 8 inches to 2 feet high; nodes 

 sometimes slightly pubescent ; sheaths glabrous to strongly papillose-pubescent ; 

 blades 2 to 6 inches long, 3 to 6 lines wide, glabrous or papillose-hispid beneath ; 

 panicles long-exserted, finely pubescent and copiously papillose-hirsute, 3 to 9 

 inches long, the branches solitary, ascending, few-flowered; spikelets nearly 2 

 lines long, obovate-elliptical, abruptly pointed, densely hirsute to glabrous, 

 borne on very short appressed branchlets. 



Open ground; Jamacha, San Diego Co., Canby (the only California specimen 

 seen) to western Texas and south into southern Mexico. 



Ref. PANICUM ARIZONICUM Scribn. & Merr. U. S. Dept. Agr. Div. Agrost. Circ. 32: 2. 1901. 



2. P. dichotomiflorum Michx. Annual, usually much-branched from a ge- 

 niculate base, smooth throughout; culms rather succulent, 2 to 3 feet high; 

 blades 4 to 20 inches long, about y 2 inch wide ; panicles 4 to 12 inches long, 

 finally spreading; spikelets l 1 ^ lines long, narrowly oblong-ovate, acute, 

 faintly 7-nerved, the first glume short, truncate, about 14 the length of the 

 spikelet. 



Low ground and cultivated soil; Fresno, Bioletti 140, the only California 

 specimen seen. Common in Eastern U. S. 



Eefs. PANICUM DICHOTOMIFLORUM Michx. Fl. Bor. Am. 1: 48. 1803. This species has 

 been incorrectly referred by American botanists to P. proliferum Lam. of the Old World. 



3. P. capillare L. OLD-WITCH GRASS. Annual, erect, 1 to 2 feet high ; foli- 

 age papillose-hispid ; blades 4 to 10 inches long, i/4 to % inch wide ; panicle 

 large and diffuse, often % the length of the entire plant, included at the base 

 until maturity, the whole panicle finally breaking away and rolling before the 

 wind; spikelets about 1 line long, elliptic; first glume acute, y 2 as long as 

 spikelet, 5 to 7-nerved. 



Open ground, cultivated soil, and river banks, a common weed in Eastern 

 U. S. Pinegrove, Amador Co., Hansen 599, the only specimen seen from Cali- 

 fornia. 



Refs. PANICUM CAPILLARE L. Sp. PI. 58. 1753. The species described under this name 

 in western floras is usually P. barbipulvinatum. 



4. P. barbipulvinatum Nash. Closely resembling P. capillare of which it is 

 the western representative, but differing in its stouter habit, shorter, less 

 pubescent blades crowded toward the base of the plant, and especially in the 

 larger spikelets, about iy 2 lines long. 



Open ground and cultivated soil at moderate altitudes throughout the state 

 and extending from British Columbia to Texas. 



