106 GEAMINEAE (GRASS FAMILY) 



19. P. linearifblium Scrlbn. Densely tufted, 2-4.5 dm. high ; culms very 

 slender, erect, spreading or almost drooping at the summit; sheaths usuallj 

 equaling or exceeding the interiiodes, 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 \-\ 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 Out., Pa., O., and Mo. — In the field resembles P. depauperatum. 



+- 2, Laxiflbra. — 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-pilo.ie with refl.exed 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 

 flexuoxts 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. laxifiorum 

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



22. P. strig6sum 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 (1.3-1.6 mm. long) ; second glume and sterile lemma equal, as long as 

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



■I- 3. Angustifblia. — 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, puiescetit (rarely glabrous); first glume 1-nerved; second glume 

 and sterile lemma equal, 1 -Si-nerved; fruit broadly ellipsoidal. 



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

 m. 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, vej'y narrow, flat, or involute on the margins 

 only. — Low sandy woods, Del., Va., and southw. — Variable in the amoun't 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 narrowly ascending; spikelets more turgid, more densely villous. 

 Branching state decumbent ; the numerous leaves soft and flat, rarely over 6 cm. 

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



26. p. *cicul?lre Desy. Ascending-pilose ; culms at first ascending or spread- 



Y. 



