548 GRAJiiNE^E. (grass family.) 



48. AMPHICARPUM. Spikelets of two kinds ; one disposed in a terminal panicle, perfect but 



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



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



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



50. SETARIA. Spikelets crowded in spike-like panicles, subtended by a bristle-like involucre- 

 61. CENCHRUS. Spikelets single, or few in a cluster, enclosed in an indurat<^d and spiny in- 

 volucre. Spikelets spiked. 



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



Panicum. 



Teibe IX. ROTTBtEIiIilACE.^ Spiliclets 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 glume 

 coriaceous or cartilaginous. Palese awuless. 



53. ROTTBQULLIA. 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. 



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



tillate. 



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

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



56. ANDROPOGO-V. Spikelets 2 on each joint of the plumose or hairy rachis, one sessile and 



perfect, the other stalked and imperfect or rudimentary. 



57. ERIANTHUS. 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. liEEBSIA, Swartz. False Rice. 



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

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

 1-sided panicled racemes. Pedicels jointed. Glumes none. Paleoe 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 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. L. Virginica, WiUd. Panicle nearly simple, the lower branches spread- 

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

 1-2. (L. imbricata. Lam.'?) — Swaraps and margins of streams, Florida, and 

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

 half as large. 



3. L. lentieularis, Michx. Panicle diffuse ; spikelets oval, 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. Spikelets 3" long. 



