ORDER CXLIT. GRAMINACE^. 581 



3. 0. murica'tus, (Kunth.) {Panicum Walteri, Pursh.) Stem erect, 

 Blender, glabrous. Leaves horizontal, glabrous; throat of the sheath 

 ciliate. Flowers in alternate spikes, in three rows ; rachis scabrous. 

 Glumes 2-flowered, perfect and sterile. — 0. Through the summer 

 In damp soils. Low country. 2 — 3 feet. 



Genus XIII.— SETA'RIA. Beauv. 

 (From seta, a bristle.) 



Spikelets 2-flowered, invested with an involucre of two or 

 more bristles. Glumes 2, unequal ; lower flower abortive. 

 Palece 1 — 2, herbaceous ; upper flower perfect. Palece carti- 

 laginous. Flowers in compound, cylindrical spikes. 



1. S. glau'ca, (Beauv.) {Panicum glaucnm, Ell.) Stem erect, gla- 

 brous, slightly compressed. Leaves linear-lanceolate, acute ; upper 

 surface scabrous ; spike cylindrical. Glumes with an accessory one, 

 acute, 3-nerved. Palece 2, the exterior one obscurely 5-nerved. Awns 

 8 — 10, in two fascicles. — 0. July — Aug. Roadsides. 2 feet. 



There are two or three varieties of this plant, varying in the direction of tho stem, 

 and in the number of the flowers in the spikelets, and in being pubescent. 



2. S. corruga'ta, (Schul.) (Panicum corrugatum, Ell.) Stem erect, 

 terete, slightly scabrous. Leaves acute, scabrous ; sheaths longer than 

 the joints. Flowers in compound, compact spikes; spikelets with about 

 half the flowers fertile, the others sterile. Glumes with an accessory 

 valve, 5-nerved. Palece as long as the glumes, the exterior one wrin- 

 kled. — 71. Through the summer. Low country. 2 — 3 feet. 



3. S. l^kviga'ta, (Schul.) (Panicum Icrvigaturn, Muhl.) Stem pro- 

 cumbent, compressed, the upper joints longest. Leaves narrow, gla- 

 brous ; sheaths compressed ; spike columnar ; spikelets 1-ftowered. 

 Involucels 10-awned. — If. Through the summer. Sea-islands. 1 — 2 

 feet. 



4. S. affi'nis, (Schul.) Leaves linear-lanceolate, pilose ; sheaths stri- 

 ate ; ligi.le bearded. Peduncles pubescent ; bracts purple at the 

 apex. Flowers in elongated fascicles. — Geo. to Penn. 



5. S. Ital'ica, (Kunth.) (Panicum Italicum, L.) Stem, erect, slightly 

 compressed, tomentose. Leaves very long, channeled, scabrous, the 

 sheath with the throat and margins ciliate ; spikes compressed, with 

 the spikelets many-flowered. Involucre longer than the flowers. Glumes 

 2-flowered, only one palese to the sterile floret. — 2T.. Aug. — Sept. 

 Wet soils. 2 — 10 feet. 



Genus XIV.— CEN'CHRUS. Beauv. 

 (A Greek name of Setaria Italica.) 



Involucre 1 — 3-flowered, many-parted, bristly. Glumes 2, 

 2-flowered, exterior ones smallest ; the exterior floret sterile, the 

 other perfect Palece 2, unawned. 



