704 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 





Figtxre 1076. — Panicum urvilleanum. Two views of spikelet, and floret, X 10. (Type.) 



to a long involute setaceous point, 

 strigose or glabrous; panicle 25 to 30 

 cm. long, the slender branches ascend- 

 ing; spikelets 6 to 7 mm. long, densely 

 silvery- or tawTry-villous; first glume 

 clasping, from two-thirds to nearly as 

 long as the spikelet. % — Sandy 

 deserts, Arizona and southern Cali- 

 fornia; Argentina, Chile. 



15. Obtusa. — Stoloniferous wiry per- 

 ennial; ligules about 1 mm. long; 

 panicles narrow, the few ap- 

 pressed branches densely flow- 

 ered; spikelets short-pediceled, 

 secund, glabrous; fruit smooth 

 and shining. 

 168. Panicum obtusum H. B. K. 

 Vine-mesquite. (Fig. 1077.) Tufted 

 from a knotted crown, the stolons 

 sometimes 2 m. long or more, with 

 long internodes and geniculate, swol- 

 len, conspicuously villous nodes; 

 culms compressed, 20 to 80 cm. tall; 

 blades mostly elongate, 2 to 7 mm. 

 wide, glabrous or nearly so; panicles 

 3 to 12 cm. long, about 1 cm. wide; 

 spikelets 3 to 3.8 mm. long, obovoid, 

 brownish, obtuse; first glume nearly 

 as long as the spikelet. 91 — Sandy 

 or gravelly soil, mostly along banks 



of rivers, arroyos, and irrigation 

 ditches, western Missouri to Colo- 

 rado, south to Arkansas, Texas, 

 Utah, and Arizona; Mexico. 



16. Hemitonia. — Aquatic or subaqua- 

 tic perennial; panicles elongate, 

 very narrow; spikelets subsessile, 

 3- to 5-nerved, glabrous. 

 169. Panicum hemitomon Schult. 

 Maidencane. (Fig. 1078.) With ex- 

 tensively creeping rhizomes, often 

 producing numerous sterile shoots 

 with overlapping, sometimes densely 

 hirsute, sheaths; culms 50 to 150 cm. 

 tall, usually hard; sheaths of fertile 

 culms usually glabrous; blades 10 to 

 25 cm. long, 7 to 15 mm. wide, usu- 

 ally scabrous on the upper surface 

 and smooth beneath; panicle 15 to 30 

 cm. long, the branches erect, the 

 lower distant, the upper approximate, 

 2 to 10 cm. long; spikelets 2.4 to 2.7 

 mm. long, lanceolate, acute; first 

 glume about half the length of the 

 spikelet; fruit less rigid than usual in 

 the genus, the apex of the palea 

 scarcely enclosed. % — Moist soil 

 along river banks and ditches, borders 

 of lakes and ponds, often in the water, 

 sometimes a weed in moist cultivated 



