548 ckamixe.e. (grass family.) 



48. AMPIIICARPUM. Spikelets of two kinds; one disposed in a terminal j>anicle, perfect but 



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



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



49. PAXICl'M. Spikelets single, without a bristly or spiny involucre. 



50. SETAR] A. Spikelets crowded in spike-like panicles, subtended by a bristle-like involucre. 



51. CENCHR1 Si Spikelets single, or few in a cluster, enclosed in an indurated and spiny in- 



volucre. Spikelets spiked. 

 62. STEXOTAl'HRUM. Spikes and spikelets mostly as in Rottboellia, but the flowers as iu 

 Panicum. 



Tribe IX. ROTTBCEL.L.IACEJE. — 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 glume 

 coriaceous or cartilaginous. Palese awnless. 



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



perfect. 



54. MAMSI R1S. 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. AKDROPOGONE.i;. — Spikelets 2 - 3 on each joint of the slender hairy or 

 plumose rachis. Glumes more rigid than the thiu-awned palesc. 



56. AXDROl'OOON. Spikelets 2 on each joint of the plumose or hairy rachis, one sessile and 



perfect, the other stalked and imperfect or rudimentary. 



57. EU1ANTI1US. Spikelets 2 on each joint of the rachis, both fertile and surrounded by a 



hairy iuvolucre. 



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



1. LEERSIA, Swartz. False Eice. 



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

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

 1-sided panicled racemes. Pedicels jointed. Glumes none. Palcaj 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 imhricated ; 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, ahout 3" long. 



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

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

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

 northward .Inly and Aug. — More slender than the last, and with Bpikeleta 



half as huge. 



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

 fringed, closely imbricated; stamens 2. — Ponds ami swamps, Florida to North 



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

 ing, somewhat glaucous. Spikelets 3" long. 



