548 GKAMINK-K. (CKASS FAMILY.) 



48. AMPHICARPTJM. Spikelets of two kiuds ; one disposed ia a terminal panicle, perfect but 



eeldom fruiting ; the other fruitful, on long Bolitary radical peduncles. 



« * Glumes 2, the lower one often minute, rarely wanting. 



49. PANICUM. Spikelets single, without a bristly or spiny inrolucre. 



60. SET.\KIA. Spikelets crowded in spike-like panicles, subtended by a bristle-like involucre. 



51. CENl'lIRUS. S|iikelets single, or few in a cluster, enclosed in an indurated and spiny in- 



volucre. Spikelets spiked. 



52. STKXOTAPllRUM. Spikes and spikelets mostly as in Rottboellia, but the flowers as in 



Panicum. 



Tribe IX. ROTTBCELIjI ACE.^. — Spikelets 1 - 2-flowered, by pairs, imbedded in 

 an excavation of the thick and jointed rachis, one stalked and imperfect, the other sessile 

 and perfect ; or tho upper spikelets all staminate and the lower pistillate. Lower glume 

 coriaceous or cartilaginous. Palese awnless. 



63. ROTTBCELLIA. Spikelets 2 on each joint, one stalked and sterile, the other sessile and 

 perfect. 



54. MANISURIS. Spikelets 2 on each joint, the one at the top of the joint sterile, the other 

 at the base globose and fertile. 



66. TUIPSACUM. Upper spikelets by pairs, all staminate ; the lower ones single, and pis- 

 tillate. 



Tribe X. AIVDROPOGOKEjE. — Spikelets 2 - 3 on each joint of the slender hairy or 

 plumose rachis. Glumes more rigid than the thin-awned paleae. 



66. ANDIIOPOGOX. Spikelets 2 on each joint of the plumose or hairy rachis, one sessile and 



perfect, the other stalked and imperfect or rudimentary. 



67. ERIAN'TIIL'S. Spikelets 2 on each joint of the rachis, both fertile and surrounded by a 



hairy involucre. 



68. SORGHUM. Spikelets panicled, 2-3 together, the lateral ones rudimentary. 



1. LEERSIA, Swartz. False Kice. 



Perennial aquatic or marsh grasses, vnth the leaves and sheaths roughened 

 witli minute recurved points, the 1-flowered (whitish) spikelets crowded in 

 l-sidcd panicled racemes. Pedicels jointed. Glumes none. Palca; 2, charta- 

 ceous, strongly compressed, fringed on the keel, the lower one much wider. 

 Stamens 1-6. Stigmas 2. Grain compressed. 



1. L. oryzoides, Swartz. Panicle large, diffuse; spikelets oblong, flat, 

 loosely imi)ricated ; stamens 3. — Ditches and swamps, Florida, and northward. 

 July and Aug. — Culm 3° -4° long, commonly prostrate at the base. Leaves 

 spreading. Base of tlie panicle mostly enclosed in the sheath of the subtending 

 leaf. Spikelets strongly fringed, about 3" long. 



2. L. Virginica, Willd. Panicle nearly simple, the lower branches spread- 

 ing ; spikelets small, concave, sparingly fringed, closely imbricated; stamens 

 1-2. (L. imbricata, Tmiii.?) — Swamps and margins of streams, Florida, and 

 northward July and Aug. — More slender than tho last, and with spikelets 

 half as large. 



3. L. lenticularis, Michx. Panicle diffuse ; spikelets oval, flat, strongly 

 fringed, closely imbricated ; stamens 2. — I'onds and swamps, Florida to North 

 Carolina, and westward. Aug. — Culm 2° -3° long. Leaves widely spread- 

 ing, somewhat glaucous. Spikelets 3" long. 



