106 GRAMINEAE (GRASS FAMILY) 



19. P. Iinearif61ium 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 J-^ 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. Werndri 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 wanting. Sterile woods and 

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



i- 2. Laxiflora. 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. xalapnse 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 glabrous except 

 the ciliate margins; panicle finally exserted, 6-10 cm. long, lax, the capillary 

 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. strigbsum 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 mm. long) ; second glume and sterile lemma equal, as long as 

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



1-3. Angustifolia. Mostly grayish-green, caespitose; primary culms with 

 elongated leaves (tapering to each end) and long-exserted few-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, 7-9-nerved ; fruit broadly ellipsoidal. 



23. P. angustif blium 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 4-9 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, ^ 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. cpnsangulneum 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 narrowly 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 spread- 



