GRAMINEiTi:. ((iUASS FAMILY.) G31 



oblong and pointed, nearly eqiialliug tlie lance-oblong ohtnsisli empty glumes. 

 — Saud-liills, Jll. to Minn., JMo., and southward. 



H- -1- iSterile Jiowcr rudimentary (staminate in n. 7), its f/lume fully twice the 

 Itwjth of the lower (]lume ; spikelets small (1 or H" long); root perennial. 



5. P. Anceps, Michx. Culms flat, upright (2-4° high); leaves rather 

 liroadly linear (1-2° long, 4 - 5" wide), smooth; panicle contracted-pyrami- 

 dal; spikelets ovate-lanceolate, pointed, a little curved; second glume 5-7- 

 nerved ; neutral flower one third longer than the perfect one. — Wet sandy 

 soil, N. J. and Penn. to S. 111., and soutlnvard. Aug. — Sj)ikelets larger and 

 Itranclics of the ])aiii(lc longer and narrower than in the next. 



ti. P. agrostoides, iMulil. Culms Jlattmcd, upright {2 -4° h\}^\\) ; loaves 

 long, and with tlie sheaths smooth ; panicles terminal and often lateral, pyram- 

 idal (4-8' long); spikelets racemose, crowded and one-sided on the spread- 

 ing Iiranclies, ocaje-oblong, acute (purplish) ; second glume b-nerved, longer than 

 the neutral flower; perfect flower shorter, bearded at the apex. — Wet mead- 

 ows and shores, E. Mass. to Minn., Neb., and common soutiiward. Aug. 



7. P. Curtisii, Cliapm, Culms stout, 3 - 4° high, often rooting below; 

 mostly glabrous; panicle slender, simple, spike-like (6-8' long), the spikes 

 appressed ; spikelets lanceolate, acute ; lower glume half the length of the 

 5-uerved second one. — Ponds, Del. to Fl. and Tex. 



-<- -I- -*- Sterile flower staminatc ; lower glume more than half the length of the 

 next; spikelets large (2-2^^" long), ocate, pointed, as are the glumes, etc.; 

 perennials, glabrous, with tall or stout and rigid upright culms. 



8. P. virgatum, L. (PI. 13, fig. 8, 9.) Tall (3-5° high) ; leaves very 

 long, flat ; ligule silky-bearded ; branches of the compound loose and large pani- 

 cle (9' -2° long) at length spreading or drooping ; spikelets scattered, usually 

 purplisli. — Moist sandy soil ; common. Aug. 



9. P. am^rum, Ell. Culms (1^° high or more) sheathed to the top; 

 h'drra inrohile, glaucous, coriaceous, the uppermost exceeding the contracted pan- 

 irle, the simj)le racemose branches of which are appressed; spikelets pale. — 

 Sandy shores, Cimn., Va., and southward. Aug., Sept. — The northern form 

 (var. MINUS, Vasey & Scribn.) somewhat smaller tliau the southern. 



* * Panicle short or small, loosely spreading or diffuse ; perennials. 

 •4- Sterile flower none ; spikelets warty roughened. 



10. P. verrucdsum, Muhl. Smooth; culms branching and spreading, 

 very slender (1 -2° long), naked above; leaves linear-lanceolate (2-3" wide), 

 shining; branches of the diffuse panicle capillary, few-flowered; spikelets 

 dark green, oval, acute, f h^ng ; lower glume { as long as the faintly nerved 

 second. — Sandy swamps, N. Eng. to Va., near the coast, and southward. 



-I- -»- Lower {sterile) flower neutral, or in n. \2and sometimes in n. 11 staminatc, 



the palet scarious and sometimes small and inconspicuous. 



-M. Culm4eaves broadly lanceolate or wider, with 0-15 principal jicnrs {obscurt 



or none in n. 17). 



= Spikelets 1-1^" long. 



11. P. xanthophysum, Gray. Culm simple, or at length branched 

 near the base (9- 15' high) ; sheaths hairy ; leaves lanceolate, very acute (4-6' 



