106 GKAMINEAE (GRASS FAMILY) 



19. P. Iinearif51ium Scribn. Densely tufted, 2-4.5 dm. high; culms very 

 slender^ erect., spreading or almost drooping at the summit; sheaths usually 

 equaling or exceeding the internodes, sparsely to densely papillose-pilose ; blades 

 1-3.5 dm. long, 2-4 mm. wide, usually exceeding the panicle until maturity, 

 often pubescent below ; panicles finally long-exserted, 5-10 cm. long, rather few- 

 flowered, the remote flexuous branches spreading ; spikelets 2.4-2.7 mm. long, 

 subacute^ sparsely pilose ; first glume i-^ the length of the spikelet, triangular- 

 ovate ; second glume and sterile lemma equaling the fruit at maturity; fruit 2 

 mm. long. — Woods, Me. to Md., w. to Mich, and Kan. 



20. P. Werneri Scribn. Similar to the preceding ; in small tufts, glabrous 

 except for a few long hairs at the nodes and base of blades; culms strict; leaves 

 firmer, 1.5 dm. long or less, 3-6 mm. wide ; spikelets 2.2-2.3 mm. long, nearly 

 or quite glabrous; secondary panicles usually icanting. — Sterile woods and 

 knolls, Me. to Ont., Pa., O., and Mo. — In the field resembles P. depauperatum. 



-I- 2, Laxifibra. — Plants in soft tufts, light green ; culms slender, simple or 

 rarely branching from the lower nodes; basal leaves short., in a dense soft 

 tuft, but not distinctly different from culm-leaves in shape; spikelets obovate^ 

 turgid. 



21. P. xalap^nse HBK. Ascending or spreading, 1-4 dm. high ; culms lax, 

 glabrous; nodes bearded; sheaths papillose-pilose with reflexed hairs; blades 

 mostly 8-12 cm. long, 7-11 mm. wide, sparingly pilose or nearly glabro\is except 

 the ciliate margins; panicle finally exserted, 6-10 cm. long, lax, the capillai'y 

 flexuous branches spreading or drooping, few-flowered; spikelets 2 mm. long; 

 first glume glabrous ; second glume and sterile lemma villous, the glume shorter 

 than the fruit which is 1.5 mm. long and minutely umbonate. (P. laxiflorum 

 Am. auth., not Lam.) — Low woods, Md. to Mo., and south w. 



22. P. strig5sum Muhl. Erect or ascending, 2-4.5 dm. high ; culms pilose ; 

 sheaths and blades long-pilose, clustered at the base, 4-8 cm. long, 6-9 mm. wide, 

 upper blades reduced; panicle finally long-exserted, 4-10 cm. long, the axis 

 pilose, the capillary branches ascending, with numerous long-pediceled glabrous 

 spikelets (1.3-1.5 7nm. long) ; second glume and sferile lemma equal, as long as 

 the fruit. — Sandy woods, se. Va. to Tenn., and south w. 



•1-3. Angustifolia. — Mostly grayish-green, caespitose ; primai'y culms with 

 elongated leaves (tapering to each end) and long-exserted feio-flowered 

 primary panicles ; blades conspicuously striate-nerved ; ligulea ring of stiff 

 hairs less than 1 mm. long; autumnal state repeatedly bushy-branched 

 above, often geniculate-decumbent ; spikelets obovoid, turgid, attenuate at 

 the base, pubescent (rarely glabrous); first glume \-nerved ; second glume 

 and sterile lemma equal, l-'d-nerved ; fruit broadly ellipsoidal. 



23. P. angustif51ium Ell. Culms slender, erect or spreading at the top, 3-8 

 dm. high, appressed-pubescent ; nodes not bearded; sheaths shorter than the 

 internodes, papillose-pilose, lower commonly purplish ; blades ciliate toward the 

 base, 8-15 cm. long, 3-6 mm. wide, somewhat spreading, the lower shorter and 

 often broader ; panicle 4-1) cm. long, the slender flexuous branches widely spread- 

 ing, sometimes drooping, bearing a few long-pediceled spikelets about 2.5 

 mm. long ; first glume obtuse, glabrous, i the length of the spikelet or less ; 

 second glume and sterile lemma obtuse, short-villous, equaling the fruit, which 

 is minutely pubescent at the obscurely umbonate apex. Branching state lean- 

 ing, not prostrate ; leaves reduced, very narrow, flat, or involute on the margins 

 only. — Low sandy woods, Del., Va., and southw. — Variable in the amount of 

 pubescence. 



24. P. consanguineum Kunth. In the simple state similar to the preceding, 

 but spreading or ascending, more softly and densely villous; nodes bearded; 

 the leaves often conspicuously longitudinally wrinkled ; panicles smaller, the 

 branches narrovjly ascending; spikelets more turgid, more densely villous. 

 Branching state decumbent ; the numerous leaves soft and flat, rarely over 5 cm. 

 Long. (P. villosum Ell.) — Low sandy woods, se. Va., and southw.. 



25. P. aciculare Desv. Ascending-pilose ; culms at first ascending or spreg-d- 



