272 MONOCOTYLODEiVOUS. 



1 C EcHiNATUs. Slem erect, or pubescenf. Spikes consisting of 6-10 

 heads ; spikelets approximate. Involucre 10-parted, villous. 



<|> Au». — Sept. Sandy soils. 1-2 ft. 



2 C Tribuloides. Stem erect, compressed, sometimes branched. Leaves 

 scabrous on the upper suiface, ijhibrous beneath. Sheath twice the length of 

 the joints. Glumes unequal, 2-flowered,. Falece 2, the exterior valve acuce. 



July — Oct. Sandy soils. 12-15 in. 



Gends XIII TRIPSACUM. 



Flowei's monosc'ious. Sterile Jlorets, Stamens^. Glumes 

 2, 2.flo\vei*ed, outer one sterile, the interior neuter. Palea 1, 

 membrfinous. Ferdle flowers. Glumes 2, l-flowcred, sur- 

 rounded by an involucre. PalecE 2. Styles 2. Seed 1. 



1 T Dactyloides. Slem erect, glabrous, more or less compressed. Leaves 

 large, contracted at the hase. Sheath, villous at the throat. Flowers in 3- 

 clustered spikes, the upper florets sterile, the lower feriile, generally 2-4. 



%. July— Aug. Oa dry soils. 5-7 ft. 



2 T MoNOSTACHYO.v S/r-m erect, glabrous, compressed. Leaves large* 

 serrulate, contracted at the base- Flowers in a solitary, terminal spike, up- 

 per florets sterile, the lower fertile. 



Qj- Aug.— Oct. Along the sea cost. 3-5 ft. 



C. STIPACE^. 



Inflorescence panicled, consisting of one flowered, solitary 



spikelets. 



Genus XIV STIPA. 



Glumes 2, memhranous, l-flo\vered. PalecB 2, coriaceous, 

 shorter than the "flumes, the lower one with a long terminal 

 awn, the upper oae entire. Panicle lax. 



1 S xA.VENACEA. S/em erect, terete, glabrous, lower leaves longest, glabrous 



beneath, scabrous on the upper surface- Flowers in difl^use panicles- Glumes 



nearly equal, concave, sometimes awned. Palace stiped, the sfipe bearded. 



iLu;n spiral. Feathergrass. 



1\. June. Sandy soils, common- 2-3 ft. 



D. bROME^, 



Infloresence panicled, consistinor of solitary spikelets or ra- 

 ce nes, 2, or many flowered. Glumes keeled, PalecB resem- 

 bling the glumes, the lower one keeled, or concave, bearded, 

 the upper with 2 keels. 



Genus XV ARISTIDA. 



Glumes 2, membranaceous, unequal. Palece 2, on pedi- 

 cels, lowar one coriaceous, 3.avvned, the upper one very small, 

 or wanting. Scales collateral. 



1 A DicHOTOMA. Stem slender, branching, glabrous. Leaves narrow, flat 



