ORDER- CXLII. — GEAMLNACB.fi. 577 



flowered, perfect and sterile ; valves acute, hairy. Palece of the sterile 

 floret 1. — U- Aug. — Sept. On the sea-islands. 4 — 6 feet. 



2. P. sanguixa'lis, (L.) {Digitaria saugiunalis, Scop.) Stem decum- 

 bent and assurgeut, geniculate, taking root at the joints. Leaves hairy, 

 with the sheaths shorter than the joints, sometimes purple ; spikes 

 digitate, spreading, 4 — 6. Glumes glabrous, exterior ones small. Pa- 

 lece with the valves equal, lanceolate. — ©. Through the summer. 

 Cultivated grounds. Very common. Crab-grass. 



§ 2. Spikes racemose. 



3. P. Elliottia'nvm, (Schult.) (P. gibbum, Ell.) Stem erect, gla- 

 brous. Leaves linear-lanceolate, pubescent. Flowers in appressed ra- 

 cemes. Glumes 2-flowered, perfect and sterile. Palcw of the perfect 

 flower about half the length of the glumes. — %. Through the summer. 

 Damp soils. Common. 1 — 2 feet. 



§ 3. Branches paniculate, more or less divided; spikel els solitary, scat- 

 tered. 



4. P. ignora'tum, (Kunth.) {Aulaxanthus ciliatus, Ell.) Stem erect, 

 glabrous, compressed toward the base. Leaves linear, ciliate, glabrous ; 

 sheath ciliate, hairy at the throat. Glumes villous. Palece brown, 

 nearly black when mature. — 2£. Sept. — Oct. Pine-barrens. 1 — 2 ft. 



5. P. ru'fum, (Kunth.) {Aulaxanthus ruj 'us, Ell.) Stem erect, larger 

 than the preceding. Leaves glabrous. Panicle large. Glumes cov- 

 ered with long, reddish-brown hair. — If. Aug. — Sept. Damp soils. 

 2—3 feet, 



6. P. deb'ile, (Poir.) (P. hians, Ell.) Stem slender, decumbent, gla- 

 brous. Leaves linear, ciliate near the base ; sheaths short, contracted 

 and pubescent at the throat. Flowers in racemose panicles. Glumes 

 ovate, acute, 2-flowered ; valves of the sterile floret long, of the fertile 

 ovate, cartilaginous. — 0. Aug. — Oct. Pine-barrens. Common. 10 

 — 15 inches. 



I. P. prolif'erum, (Lam.) (P. geniculatum, Muhl.) Stan assurgent, 

 geniculate, branching, large. Leaves long, hairy, and scabrous on the 

 upper surface, glabrous beneath. Flowers in large panicles, diffuse. 

 Glumes 1-flowered. — If. Aug. — Oct. Wet soils. 3 — 6 feet. 



8. P. virga'tum, (L.) Stem erect, glabrous. Leaves somewhat serru- 

 late, long; sheaths shorter than the joints. Panicle large, with the 

 branches often verticillate. Glumes 2-flowered, perfect and sterile, 

 with an accessory valve. — If. Aug. — Sept. Sea-coast. 4 — 6 feet. 



9. P. scabrius'ctlum, (Ell.) Stem erect, large, somewhat pubescent, 

 scabrous. Leaves linear-lanceolate, pubescent beneath, serrulate ; 

 sheaths pubescent, hairy at the throat Panicles large, expanding. 

 Peduncles glabrous. Glumes 2-flowered, perfect and sterile. — %. 

 Sept, — Oct. Low country of Geo. 2 — 3 feet. 



10. P. multiklo'rum, (Poir.) Smooth. Panicle dense, many-flow- 

 ered. Flowers sub-acute, oblong, small; branches rough. Leaves 

 broad, linear, smooth. — Car. 



II. P. ama'rum, (Ell.) Stem erect, stout, glabrous. Leaves flat, 

 thick ; throat of the sheath contracted, purple. Panicle large. Flow- 

 ers large. Peduncles glabrous. Glumes 2-flowered, tinged with pur- 



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