GRAMINE^. (grass FAMILY.) 631 



oblong and pointed, nearly equalling the lauce-oblong obtusish empty glumes. 



— ISaud-liills, 111. to iNIiuu., Mo., aud southward. 



•t- H— Sterile flower rudimentary (staminate in n. 7), its ylume fulltj twice the 

 lengtli of the lower glume ; spikelets small (1 or 1^" long); root perennial. 



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

 broadly 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 southward. Aug. — Spikelets larger and 

 branches of the panicle longer and narrower than in the next. 



6. P. agrostoides, Muhl. Culms flattened, upright (2 -4° high) ; leaves 

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

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

 ing branches, ovate-oblong, acute (purplish) ; second glume 5-7ierved, longer than 

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

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



7. P. Curtisii, Chapm. 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-nerved second one. — Ponds, Del. to Fl. and Tex. 



— s- -t- Sterile flower staminate ; lower glume more than half the length of the 



next; spikelets large (2-2^" long), ovate, 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 

 purplish. — Moist sandy soil ; common. Aug. 



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

 leaves involute, glaucous, coriaceous, the uppermost exceeding the contracted pan- 

 icle, the simple racemose branches of which are appressed ; spikelets pale. — • 

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

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



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



-I- Sterile flower none ; spikelets warty roughened. 



10. P. verrucosum, 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" long ; lower glume | as long as the faintly nerved 

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



-- -•- Lower {sterile) flower neutral, or in n. 12 and sometimes in n. 11 staminate, 



the palet scarious and sometimes small and inconspicuous. 

 -*■ Culmdeaves broadly lanceolate or wider, with 9-15 principal nerves {obscurs. 



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' 



