782 Order 156.— GRAMINE^E. 



3 P. aetaceum Mx. Culm ascending from a decumbent base, very slender, 1 to 

 2f, with very remote joints; lvs. lance-linear, 3 — 7' by 2 — 3", ciliate and soft 

 hairy ; sheaths pubescent, upper one very long ; spike generally solitary, often 2, 

 on a long, very slender peduncle, sometimes with another scarcely exserted from 

 the sheaths ; spikelets plano-convex, with the flat side out, f " diam., 1 or 2 on 

 each very short pedicel, appearing 2 — 3-rowed in the 1-sided spike. — Dry fields, 

 Mass., to 111. and S. States. Aug. (P. debile and ciliatifolium Mx.) 



/3. longipedunculatum. Larger, less hairy, and spikelets evidently 3-rowed. 

 — S. States. (P. longip. LeC.) 



4 P. leeve Mx. Culm erect, rather firm, 18' — 3f, glabrous; lvs. generally smooth, 

 pilous only at the base, broadly linear; lower sheaths sometimes hairy, spikes 

 2 — 6, alternate, spreading, with a few long, white hairs at the base ; spikelets in 2 

 rows; rachis flexuous, flat on the back; pedicels undivided, with one spikelet; 

 spikelets twice as large (1£" diam.) as in the preceding ; glume orbicular-ovate, 

 3-veined. — Grassy banks of rivers, Conn, to Ind. and S. States. Aug. Quite vari- 

 able, including several reputed species. 



/?. dndulosum. Lvs. rather long and broad, with wavy-margins. (P. Lecon- 



tianum Schult.) 

 7 . Floridanuji. Spikelets enlarged (near 2" long), glume 5-veined. (P. ma- 



crospermum Flgg.) 

 J. altissimum. Strict and tall ; sheaths much compressed. (P. altissimum LeC.) 



5 P. angustifolium Le Conte. Culm erect, wiry, glabrous, 2f high ; lvs. glab- 

 rous, narrowly linear, almost setaceous, compressed carinate, 9 to 18' long ; sheaths 

 long, smooth ; spikes 2 or 3, alternate, divaricate, 1 to 2' long, with a few hairs at 

 base ; spikelets orbicular, 1" diam. in 2 rows, with a very narrow rachis. — 2£ Wet 

 places, Ga., Pla. to La. A distinct species. Seeds blackish. 



6 P. dasyphylluin Ell. Culm decumbent at base, 12 to 30' high, glabrous; 

 lvs. broadly linear, clothed with copious soft hairs as well as the long sheaths ; 

 spikes 2 to 4, large, spreading, the ped. slightly exserted from the upper sheath ; 

 spikelets oval, obtuse, large, in 3 rows ; teeth of the rachis 2-flowered. — Dry fields, 

 S. States, common. (I)? JL — Oct. 



7 P. latifolium Le Conte. Glabrous; culm erect, stout, tall (2 to 3f), from a 

 elightly decumbent base ; lvs. flat, large, lance-linear, 6 to 12' by 5 to 10", margins 

 ciliate ; sheaths hairy at throat, shorter than the long internodes ; spikes 2 to 4, 



2 to 4' long, alternate, suberect, pilous at base; spikelets large (1£" diam.), in 



3 rows on the narrow, flexuous rachis. — 1[ Car. to Pla. and La. 



8 P. tenue Kunth. Glabrous; culm erect, very slender; lvs. narrow, very long, 

 ciliate on the margins, sheath ciliate; spikes 4 or 5, very slender, alternate, 

 spreading, hairy at base ; spikelets orbicular, in 3 rows ; rachis flexuous, narrow, 

 the teeth 2-flowered. — U N. J. to Ga. (Le Conte). Differs from No. 5, in its ciliate 

 lvs. and 3-nerved spikelets. 



9 P. arundinaceum Poir. "Glabrous; lvs. somewhat sword-shaped (com- 

 pressed-carinate), the margin scabrous ; spikes alternate, elongated ; spikelets in 

 3 rows ; gls. (gl. and pale) equal, obtuse. — Carolina." Poiret. 



10 P. precox "Walt. Glabrous throughout; culm erect; lvs. lance-linear, very 

 long ; spikes 3 to 5, alternate, dense-flowered, with a tuft of long hair at base ; 

 rachis linear, straight (not flexuous), narrower than the 3 rows of very smooth, 

 orbicular, compressed spikelets; gls. 3-veined. — U "Wet places, Car. to Pla. May. 

 — Aug. (P. lentiferum Lam.) 



11 P. fluitans Kunth. Culm decumbent and ascending 10 to 20', generally 

 floating; lvs. scabrous, lance-linear, 2 to 5' by 4 to 6"; sheaths inflated, open, 

 ciliate at base; spikes 20 to 50, 1 to 2 V long, the lower somewhat verticillate ; 

 rachis foliaceous, nearly 1" broad, covering the 2 rows of ovate, acute spikelets 

 and projecting in' a point beyond them.- — (lj River swamps, S. Ill to Va. and S. 

 States. Oct. (P. mucronatum Muhl. Ceresia, Ell.) 



12 P. Walterianum Schult. Culm decumbent, branching, ascending; lvs. 

 glabrous,. lance-linear, 2 to 4' by 3 to 5" ; sheaths open, all glabrous; spikes 2 or 

 3 on each branch, 1 to 2' long; rachis very broad (near 2"), covering the 2 rows 

 of oval, acute spikes but not projecting beyond them, — 2) Wet soils, Car. to Fla. 

 and La. Jl. — Sept. (P. vaginatum Ell.) 



