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



acuminate; first glume clasping, two thirds to three fourths as long 

 as the spikelet, acuminate or cuspidate. % — Prairies and open 

 ground, open woods, and brackish marshes, Quebec and Maine to 

 Montana, south to Florida, Nevada, and Arizona; Mexico and Cen- 

 tral America. Panicum virgatum var. cubense Griseb. Culms 

 more slender, usually solitary or few in a tuft; panicle narrower with 

 ascending branches; spikelets 2.8 to 3.2 mm long, the second glume 

 and sterile lemma not extending much beyond the fruit. % — Pine 

 woods, Coastal Plain, Massachusetts to Florida and Mississippi; 

 Michigan; Cuba. Panicum virgatum var. spissum Linder. Culms 

 from short stout knotty rhizomes. % — Nova Scotia to Penn- 

 sylvania. 



143. Panicum havardii Vasey. (Fig. 1513.) Pale green, glaucous, 

 glabrous throughout; culms robust, solitary, 1 m tall or more, 

 erect from creeping rhizomes; blades 5 to 10 mm wide, tapering 

 into long involute-setaceous tips; panicle as much as 40 cm long; 

 spikelets 6 to 8 mm long. % — Arroyos and sand hills, western 

 Texas and southern New Mexico; northern Mexico. 



144. Panicum amarum Ell. (Fig. 1514.) Glaucous and glabrous 

 throughout; culms solitary from the nodes of extensively creeping 



Figure 1510.— Distribution of 

 Panicum repens. 



Figure 1511.— Panicum gouini. Two 

 views of spikelet, and floret, X 10. 

 (Type.) 



rhizomes, 30 to 100 cm tall; blades thick, 10 to 30 cm long, 5 to 12 

 mm wide, flat, involute toward the tip, the margins smooth; panicle 

 one-fourth to one-third the height of the plant, not more than 3 cm 

 wide, the branches appressed; spikelets 5 to 6.5 mm long, acumi- 

 nate. % — Sandy seashores and coast dunes, Connecticut to 

 Georgia; southern Mississippi; Texas (fig. 1515). 



145. Panicum amarulum Hitchc. and Chase. (Fig. 1516.) CuJms 

 as much as 1 cm thick, in large bunches as much as 1 m across, 

 1 to 2 m tall, glaucous; rhizomes vertical or ascending; blades 20 

 to 50 cm long, 5 to 12 mm wide, more or less involute, pilose on the 

 upper surface near the base; panicle large, rather compact, 5 to 10 

 cm wide, slightly nodding, densely flowered; spikelets 4.3 to 5.5 mm 

 long, acuminate. 91 — Sandy seashores and coast dunes, New 

 Jersey to Virginia; Florida; Louisiana and Texas; Yucatan; Baha- 

 mas; Cuba (fig. 1517). 



9. Tenera. — Perennials; culms subcompressed, wiry; KguJes minute; 

 spikelets short-pediceled ; fruit smooth and shining. 



146. Panicum tenerum Beyr. (Fig. 1518.) Culms in small tufts 

 from a knotted crown, erect, 40 to 90 cm tall; lower sheaths pubescent 

 toward the summit with spreading hairs; blades 4 to 15 cm long, 2 

 to 4 mm wide, erect, firm, subinvolute, pilose on upper surface toward 

 base; panicles 3 to 8 cm long, very slender, terminal and axillary; 

 spikelets 2.2 to 2.8 mm long, pointed, glabrous, the pedicel usually 



