578 GRAMINEvE. (GRASS FAMILY.) 



* Bristles roughened dowmvard. 



1. S. verticillata, Beauv. Culms sparingly branched; leaves linear- 

 lanceolate, rough ahove ; spike cylindrical, compact, somewhat interrupted be- 

 low (2' -3' long) ; bristles short, single or by pairs. — Around dwellings. North 

 Carolina, and northward. Introduced. — Culm 2° high. 



* * Bristles roughened upward. 



2. S. glauca, Beauv. Culms smooth, slightly compressed ; leaves linear- 

 lanceolate, rough above; spike nearly simple, cylindrical; bristles 6-10, in 2 

 clusters, longer than the spikelets ; perfect flower transversely wrinkled. — Var. 

 L^viGATUM (Panieuni laevigatum, Ell.) has a more flattened culm, longer, nar- 

 rower and smooth leaves, and the perfect flower obscurely wrinkled. — Culti- 

 vated ground,. the var. in damp soil along the coast, Florida to North Carolina. 

 — Culms l°-3° high. Spikes 2' -3' long, pale or purplish. 



3. S. viridis, Beauv. Culms smooth, terete ; leaves lanceolate or linear- 

 lanceolate, rough ; spikes compound, cylindrical, dense ; bristles 1 - 3 to each 

 spikelet ; perfect flower finely striate and dotted lengthwise. — Around dwell- 

 ings. Introduced. June- Sept. — Culms 1°- 2° high. Spikes 1'- 2' long. 



4. S. corrugata, Schult. Culms, narrow (2" wide) leaves, and sheaths 

 rough; spikes compound, cylindrical, dense, erect or bending; spikelets 6-10 

 in a cluster ; bristles one to each spikelet, elongated ; perfect flower obtuse, 

 strongly wrinkled. (Panicum corrugatum, Ell.) — Dry soil, Florida and Georgia. 

 July and Aug. — Culms 2° - 3° high. Spikes 3' - 6' long, purple. 



5. S. COmposita, Kunth. Culms smooth ; leaves linear-lanceolate, the 

 fringed sheaths rougii-hairy at the throat ; spikes loose, compound, the lower 

 clusters scattered; bristles single or by pairs, many times longer than the spike- 

 lets ; perfect flower acute, with faint transverse lines. — Dry sandy soil along 

 the west coast of Florida, Apalachicola to Key West. June -Aug. — Culms 

 2° -4° long. Leaves 1° or more long. Spikes 6'- 12' long. 



6. S. Italica, Kunth. Culms tall (4° -8° high), smooth, branched ; leaves 

 d'-l' wide) very rough; s])ikes compound (6'- 18' long}, cylindrical, dense, 

 the lower clusters scattered ; bristles 1 - 2 to each spikelet, elongated ; fertile 

 flower smooth and even. — Swamps along the coast, Florida to North Carolina. 

 July -Sept. — This, and Penicillaria spicata, TI7/W., are commonly cultivated, 

 under the name of Millet, as green food for cattle. The latter seems to be 

 the Panicum cenchroides, Ell. 



51. CENCHRUS, L. Cock-spur. 



Prostrate or creeping grasses, with the spikelets of Panicum proper, but en- 

 closed, 1 -several together, in spiny or bristly, at length indurated and decid- 

 uous involucres ; the latter burr-like, and arranged in a terminal spike. Stamens 

 3. Styles united below. 



1. C. ectliliatUS, L. Spikes cylindrical, composed of 20 or more globular 

 involucres (3' -4' long) ; involucre downy, spiny above, and with a row of rigid 

 barbed bristles above the base, 3 - 5-flowered ; culms ascending. — Fields and 



