ORDER CXLII. GRAMINACE.E. 575 



equal. Seeds coated with the paleae. Floiucrs in spikes, ar- 

 ranged on one side of the rachis. 



1. P. flu'itans, (Kunth.) (Ceresia fluitans, Ell.) Stem procumbent, 

 creeping, assurgent, glabrous. Leaves scabrous, 2 — 3 inches long, slight- 

 ly glaucous beneath; sheaths hairy at the base; spikes numerous, 20 — 

 30, recurved ; rachis with the flowers arranged on the upper surface. 

 Ghimes dotted, white. Palece equal ; the interior one flat, the exterior 

 convex. — 0. Sept. — Nov. Swamps. 1 — 3 feet. 



2. P. Walteria'num, (Schu.) (P. vaginatum, Ell.) Stem creeping, 

 glabrous, branching. Leaves linear, short, the sheaths of the upper 

 leaves longer than the joints ; spikes 1 — 2, one of them sessile. — If. 

 Through the summer. Damp soils, low country. 12 — 18 inches. 



3. P. filifor'me, (Swartz.) (Digitaria filiformis, Ell.) Stem erect, 

 glabrous. Leaves narrow-lanceolate, slightly scabrous, and hairy on the 

 upper surface ; sheath hairy ; spikes alternate, filiform, sometimes very 

 long. Glumes pubescent, nearly equal. — U. Sept. — Oct. On poor 

 lands. 1—2 feet. 



4. P. seroti'num, (Flue.) Spikes about 5, approximate; rachis flat; 

 spikelets rather broad. Glume elliptic-lanceolate, acute, pubescent. 

 Culm decumbent ; sheaths pilose. — Car. 



5. P. nota'tum, (Flue.) Spikes 2, conjugate ; rachis flat ; spikelets 

 narrow. Glumes ovate, obtuse. — Car. s 



6. P. dis'tichum, (Ell.) Stem prostrate, creeping, geniculate. Leaves 

 short, shining ; sheath with the throat hairy ; spikes 2 — 4. Glumes 

 lanceolate. — If. Through the summer. In damp soils. Common. 



Joint-grass. 



7. P. Michauxia'nujm, (Kunth.) {Milium paspaloides, Ell.) Stem 

 ascending and decumbent, compressed, glabrous. Leaves ciliate, gla- 

 brous, 3 — inches long ; spikes digitate, conjugate. Glumes glabrous, 

 ovate-lanceolate, acute. Palece equal, shorter than the glumes. Seed 

 ovate, compressed. — 2£. June — Sept. Low country. 1 — 2 feet. 



8. P. trista'chyum, (Leconte.) Glabrous, creeping, erect in water, 

 prostrate on land. Leaves short, narrow, smooth ; sheaths broad, 

 bearded at the orifice ; spikes about 3, naked at the base. Glumes 

 ovate, in two series. — Geo. 



9. P. furca'tum, (Flue.) Spikes 2, conjugate ; rachis triquetrous. 

 Glumes ovate-lanceolate, acuminate, smooth. — Car. and southward. 



10. P. i^e've, (Mich.) Stem erect, glabrous. Leaves short, lanceolate, 

 glabrous, hairy at the throat ; spikes 3 — 6. Flowers 1 from each head ; 

 rachis a little hairy at the base. — 2£. June — Sept. Damp pastures. 1 

 —2 feet. 



11. P. Boscia'num, (Flue.) Spikes numerous; rachis flat, straight; 

 spikelets lateral. Glumes obtuse, nearly round, smooth, 5-nerved. 

 Leaves hairy at the base. — Car. 



12. P. seta'ceum, (Mich.) Stem erect, slender, glabrous. Leaves vil- 

 lous, narrow ; sheath villous ; spikes usually solitary. Floioers in Uvo 

 rows. Peduncle long. Glume equal, 3 — 5-nerved, minutely pubescent. 

 — 2£. June — Aug. Dry soils. Common. 



13. P. dasyphyl'li-m, (Ell.) Stem decumbent, glabrous. Leaves hairy, 

 broad; sheaths shorter than the joints; spikes 2 — 3, alternate. Glumes 

 3-nerved, oval, pubescent. — July to Oct. 



