MANUAL OF THE GRASSES OF THE UNITED STATES 



757 



relatively thick, the awns 10 to 15 cm long; pedicellate spikelet 1.5 

 to 2.5 cm long, the first glume with a line of punctate glands along 

 the middle, o — Pine woods, fields, and waste places, Georgia, 

 Florida, and Alabama; Arizona; tropical regions of both hemispheres. 

 The plant when fresh emits an odor like that of citronella oil. 



151. TRACHYPOGON Nees 



Spikelets in pairs, along a slender continuous rachis, one nearly 

 sessile, staminate, awnless, the other pedicellate, perfect, long-awned; 

 the pedicel of the perfect spikelet obliquely disarticulating near the 

 base, forming a sharp-barbed callus 

 below the spikelet; first glume firm- 

 membranaceous, rounded on the back, 

 several-nerved, obtuse; second glume 

 firm, obscurely nerved; fertile lemma 

 narrow, extending into a stout twisted 

 and bent or flexuous awn; palea obso- 

 lete; sessile spikelet persistent, as large 

 as the fertile spikelet and similar but 

 awnless. Perennial, moderately tall 

 grasses, with terminal spikelike soli- 

 tary or fascicled racemes. Type spe- 

 cies, Trachypogon montufari. Name 

 from Greek trachus, rough, and pogon, 

 beard, alluding to the plumose awn 

 of the fertile spikelet. 



1. Trachypogon montufari (H.B.K.) 

 Nees. Crinkle-awn. (Fig. 1679.) 

 Culms tufted erect, slender , hispid at 

 the nodes, 60 to 120 cm tall; sheaths 

 with erect auricles 2 to 5 mm long; 

 blades flat to subinvolute, 3 to 8 mm 

 wide; raceme solitary, rarely 2, 10 to 

 15 cm long; spikelets 6 to 8 mm long, 

 pubescent, the awns of perfect spike- 

 lets 3 to 6 cm long, short-plumose 

 below, nearly glabrous toward the tip. 91 — Rocky hills and 

 canyons, southern Texas, southwestern New Mexico, and southern 

 Arizona; Mexico to Argentina. 



152. ELYONTJRUS Humb. and Bonpl. 



Spikelets in pairs along a somewhat tardily disarticulating rachis, 

 the joints and pedicels short, thickened, and parallel, the sessile spike- 

 lets perfect, appressed to the concave side, the pedicellate spikelet 

 staminate, similar to the sessile one, both awnless, the pair falling 

 with a joint of the rachis; first glume firm, somewhat coriaceous, 

 dorsally flattened, the margins inflexed around the second glume, a 

 line of balsam glands on the marginal nerves, the apex entire and 

 acute or acuminate, or bifid with aristate teeth; second glume similar 

 to the first; sterile and fertile lemmas thin and hyaline; palea obsolete. 

 Erect, moderately tall perennials, with solitary spikelike, often woolly 

 racemes. Type species, Elyonurus tripsacoides. Name from Greek 

 eluein, to roll, and oura, tail, alluding to the cylindrie inflorescence. 



Figure 1678. — Heteropogon melanocarpus, 

 X 1. (Fredholm 6405, Fla.) 



