MANUAL OF THE GRASSES OF THE UNITED STATES 755 



let about 1.5 cm long, including the slender villous callus about 7 mm 

 long, this disarticulating by a long-oblique line^ the tip of the pedicel 

 thus villous on one side; awn stout, brown, geniculate, twisted below, 

 about 15 cm long, o — Sandy pine woods, open ground, and 

 fields, Florida; Cuba. The fruits resemble those of certain species of 

 Stipa such as S. spartea L. 



150. HETEROPOGON Pers. 



Spikelets in pairs, one sessile, the other pedicellate, both of the 

 lower few to several pairs staminate or neuter, the remainder of the 

 sessile spikelets perfect, terete, long-awned, the pedicellate spikelets, 

 like the lower, staminate, flat, conspicuous, awnless; glumes of the 

 fertile spikelet equal, coriaceous, the first brown-hirsute, infolding the 

 the second ; lemmas thin and hyaline, the fertile one narrow, extending 

 into a strong bent and twisted brown awn; palea wanting; glumes of 

 the staminate spikelet membranaceous, the first green, faintly many- 

 nerved, asymmetric, one submarginal keel rather broadly winged, 

 the other wingless, the margins inflexed, the second glume narrower, 

 symmetric; lemmas hyaline; palea wanting. Annual or perennial, 

 often robust grasses, with flat blades and usually solitary terminal 

 racemes; rachis slender, the lower part, bearing the pairs of staminate 

 spikelets, continuous, the remainder disarticulating obliquely at the 

 base of each joint, the joint forming a sharp-barbed callus below the 

 fertile spikelet, the pedicellate spikelet readily falling, its pedicel 

 remaining, obscured in the hairs of the callus. Type species, 

 Heteropogon glaber Pers. (H. contortus). Name from Greek heteros, 

 different, and pogon, beard, alluding to the difference between the 

 awnless staminate and awned pistillate spikelets. 



One species, H. contortus, has a world-wade distribution. It is a 

 good forage grass in the Southwest; if grazed constantly the trouble- 

 some awns do not develop. In the Hawaiian Islands, where it is 

 called pili, it is an important range grass on the drier areas; also used 

 there by the natives to thatch their grass huts. The mature fruits 

 are injurious to sheep. 



Plants perennial, less than 1 m tall; first glume of staminate spikelet usually 

 papillose-hispid 1. H. contortus. 



Plants annual, usually more than 1 m tall; first glume of staminate spikelet with 

 a row of glands along the back, glabrous 2. H. melanocarpus. 



1. Heteropogon contortus (L.) Beauv. Tanglehead. (Fig. 1677.) 

 Plants perennial, tufted; culms 20 to 80 cm tall, branched above, the 

 branches erect; sheaths smooth, compressed-keeled; blades flat or 

 folded, 3 to 7 mm wide; raceme 4 to 7 cm long, 1-sided; sessile spikelets 

 about 7 mm long, slender, nearly hidden by the imbricate pedicellate 

 spikelets, the awns 5 to 12 cm long, bent and flexuous, commonly 

 tangled ; pedicellate spikelet about 1 cm long, the first glume papillose- 

 hispid toward the tip and margins, sometimes nearly glabrous. % 

 — Rocky hills and canyons, Texas to Arizona; tropical and warmer 

 regions of both hemispheres. 



2. Heteropogon melanocarpus (Ell.) Benth. Sweet tanglehead. 

 (Fig. 1678.) Plants annual, 1 to 2 m tall, freely branching; sheaths 

 smooth, the upper part of the keel, especially of the upper sheaths, 

 with a row of concave glands; blades 5 to 10 mm wide; raceme 3 to 6 

 cm long; looser than in H. contortus; sessile spikelets 9 to 10 mm long, 



