GRAMINE^E. (GRASS FAMILY.) 631 



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

 Sand-hills, 111. to Minn., Mo., and southward. 



i" *- Sterile flower rudimentary (staminate in n. 7), its glume fully twice the 

 length of the lower glume ; spikelets small (1 or 1-J" 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-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 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. 



- -t- H- 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. virgktum, 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. am&rum, 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. M^NUS, Vasey & Scribn.) somewhat smaller than the southern. 



# * Panicle short or small, loosely spreading or diffuse ; perennial*. 

 -i- 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 " long ; lower glume | as long as the faintly nerved 

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



- H- Lower (sterile] flower neutral, or in n. 12 and sometimes in n. 11 staminate , 



the palet scarious and sometimes small and inconspicuous. 

 - Culm-leaves broadly lanceolate or wider, with 9-15 principal nerves (obscurt 



or none in n. 17). 

 = Spikelets 1 -H" long. 



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

 near the base (9-15' high) ; sheaths hairy ; leaves lanceolate t very acute (4-6' 



