GRAMINEAE (GRASS FAMILY) 



145 



135. O. ambiguns. 

 Inflorescence x '/j. 

 Spikelet x 2%. 



52. GYMNOPOGON Beauv. 



Spikelets with 1 perfect flower, sometimes 1 or 2 neuter or staminate subses- 

 sile florets above the perfect one, remote along one side of a filiform continuous 

 rhachis, forming slender unilateral spikes; rhach ilia prolonged beyond the floret 

 as a slender often awned rudiment ; glumes narrow, subequal, rigid, scabrous on 

 the strong keel, equaling or exceeding the florets ; lemma thin, bearing a slender 

 straight awn from just below the apex ; palea about as long 

 as the lemma. Perennials, with short rather broad rigid 

 leaves and numerous slender spikes, at first erect, at length 

 widely divaricate or reflexed. (Name composed of yvnv6s, 

 naked, and ir6yui>, a beard, alluding to the reduction of the 

 abortive flower to a bare awn.) 



1. G. ambiguus (Michx.) BSP. Culms tufted from a short 

 rootstock, rigid, erect or ascending, 2-5 dm. high; sheaths 

 overlapping, blades often approximate, thick, rigid, spreading, 

 4-6 cm. long, 1 cm. or more wide ; spikes solitary or in 2's 

 along a striate axis, becoming widely divaricate when exserted 

 from the sheath, spikelet-bearing to the base; awn of floret 

 longer than the glabrous lemma; rudiment long-owned. 

 ( G. raeemosus Beauv. ) Sterile sandy or gravelly ground, 

 N. J. to Mo., Fla., and Tex. Aug., Sept. FIG. 135. 



2. G. brevifblius Trin. Resembling the preceding ; culms 



more slender, from a decumbent base ; leaves 24 dm. long, 4-9 mm. wide, 

 involute in drying ; spikes usually less numerous, more distant, naked at the 

 base, spikelet-bearing from about the middle ; awn shorter than the hairy lemma ; 

 one or two sterile florets sometimes present, rudiment usually awnless. Sandy 

 ground, N. J., and south w. 



53. CHL6RIS Sw. 



Spikelets with 1 perfect floret, sessile in 2 rows along one side of a continuous 

 rhachis, forming unilateral spikes ; rhachilla prolonged behind the palea and bear- 

 ing 1 or more rudimentary awned sterile lemmas ; glumes unequal, narrow, 

 acute, keeled; lemma often ciliate on the back or margins, 

 1-3-nerved, the mid-nerve nearly always prolonged into a 

 slender awn ; palea about equaling the lemma ; grain free 

 within the lemma and palea. Usually perennial grasses with 

 flat leaves and digitate spikes. (Named for Chloris, the god- 

 dess of flowers.) 



1. C. verticillita Nutt. Culms 1-4 dm. high, erect, or de- 

 cumbent and rooting at the nodes ; sheaths compressed ; leaves 

 obtuse, light green ; spikes several in 1-3 whorls, slender, 

 5-10 cm. long ; spikelets 3 mm. long, with awns about 5 mm. 

 long; sterile lemma one. Prairies, e. Kan. and southwestw. June. At 

 maturity the inflorescence breaks away and forms a tumble weed. FIG. 136. 



136. C. verticillata. 

 Spikelet x 2. 



54. BOUTELOtTA Lag. MESQUITE GRASS 



Spikelets 1-2-flowered, crowded and sessile in 2 rows along one side of a con- 

 tinuous flattened rhachis, which usually projects beyond the spikelets ; rhachilla 

 prolonged beyond the perfect floret and bearing a sterile (rarely staminate) 

 floret, a second or third rudiment often present ; glumes unequal, keeled ; lemma 

 broader, 3 5-nerved, 3-5-toothed or cleft, 3 of the divisions usually awn-pointed ; 

 palea about the length of the lemma, bidentate, the 2 keels scabrous ; sterile 

 floret sometimes reduced to the awns, rarely obsolete. Our species perennial, 

 with narrow flat or convolute leaves, and unilateral spikes nearly sessile along 

 a common axis. (Named for Claudio Eoutelou, a Spanish writer upon flori 

 culture and agriculture.) 



GRAY'S MANUAL 10 



