548 GBAX1NEJ& (grass family.) 



48. AMPIIICARI'l'M. Spikelets of two kinds ; one disposed i;i a terminal panicle, perfect but 



seldom fruiting ; the other fruitful, on long solitary radical peduncles. 



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



49. PAXICUM. Spikelcts single, without a bristly or spiny involucre. 



60. BETAR1A. Spikelets crowded in spike-like panicles, subtended by a brie tie-like involucre. 



51. CBNCHRUS. Sj.ikelets single, or few in a cluster, enclosed in an indurated and spiny in- 



volucre. Spikelets spiked. 



52. STEXOTAl'lIRUM. Spikes and spikelets mostly as in Rottbcellia, but the flowers as in 



l'anicum. 



Tribe IX. ROTTBCELLIACEjE. — 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 the upper spikelets all staminate and the lower pistillate. Lower gluu.e 

 coriaceous or cartilaginous. Paleae awnless. 



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



perfect. 



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



at the base globose and fertile. 



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



tillate. 



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

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



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



perfect, the other stalked and imperfect or rudimentary. 



57. ERIANTHl'S. Spikelets 2 on each joint of the rachis, both fertile and surrounded by a 



hairy involucre. 



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



1. LEERSIA, Swartz. False Rice. 



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

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

 l-sided panicled racemes. Pedicels jointed. Glumes none. Paleae 2, charta- 

 ccous, 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; spikelcts ohlong, flat, 

 loosely imbricated; stamens 3. — Ditches and swamps, Florida, and northward. 

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

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

 leaf. Spikelets strongly fringed, about 3" long. 



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

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

 1 - 2. (L. itnbrieata. LatH.f) — Swamps and margins of streams, Florida, and 

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

 half as large. 



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

 fringed, closely imbricated ; Stamens 2. — Ponds and swamps Florida to North 

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

 ing, somewhat glaucous. Spikelcts 3" long. 



