GRAMINEAE (GRASS FAMILY) 115 



profusely from the upper, the short branches ar^gregated at the summit; the 

 crouxled leaves widely spreading. (P. paucijlorum Ell., not R. lir.) — Sandy 

 soil, Del. to U. C, and southw. ; and in n. Ind., near L. Michif^an. 



63. P. Scribnerianum Nash. Similar to the preceding, usually in larger 

 clumps; culms not so tall, usually less pubescent; sheaths papillose-hispid or 

 sometimes nearly glabrous ; ligule about 1 mm. long ; blades 

 ascending or erect, averaging wider (6-10 mm., rarely wider), 

 usually ciliate toward the subcordate base ; panicle short-exserted, 

 4-7 rarely 9 cm. long, about as wide ; spikelets 3.2-3.3 mm. long, 

 very turgid, obtuse, sparsely pubescent or nearly glabrous ; second 

 glume slightly shorter than the minutely apiculate fruit. Branch- 

 ing late, mostly from the lower nodes, forming short tufts. 

 (P. scoparium Wats. & Coult., not Lam.) — Sandy soil or dry 

 prairies, Me. to Ont., and westw. to the Pacific, s. to Va. and ^^- !'■ ^<^ribneri. 



Tex. Fig. 66. anum Spike- 



64. P. Leibergii (Vasey) Scribn. Cuhns 3-8 dm. high, ^^^^^'^h-. 

 scabrous, at least below the nodes ; sheaths strongly papillose-hispid, loith spread- 

 ing hairs ; ligule very minute ; blades ascending, 8-15 cm. long, 8-12 mm. wide, 

 papillose-hispid on both surfaces, often sparsely so above ; panicle 8-15 cm. long, 

 less than | as wide, the branches narrowly ascending ; spikelets 4 mm. long, less 

 turgid than in the last, papillose-hispid with long spreading hairs ; first glume 

 over \ as long as the spikelet, acuminate, second equaling the fruit. Sparingly 

 branched from the lower nodes in late summer, the branches mostly simple, 

 erect; blades not much reduced. — Prairies, O. and Mich, to S. Dak. and Mo. 



65. P. Ravenelii Scribn. & Merr. Erect or ascending ; culms 3-6 dm. high, 

 densely papillose-pubescent with ascending hairs; nodes short-bearded; sheaths 

 distant below, the upper overlapping, pubescent like the culm ; ligule 3-4 mm. 

 long; blades thick, ascending, 8-15 cm. long, 1-1.5 mm. wide, rarely wider, 

 ciliate nearly to the apex, densely pubescent beneath, glabrous above ; panicle 

 short-exserted or included at base, 7-10 cm. long, about as wide, branches finally 

 spreading ; spikelets 4 mm. long, broadly obovate, very turgid, sparsely pubes- 

 cent ; first glume about ^ as long as the spikelet, second glume slightly shorter 

 than the fruit. Autumnal state more or less spreading, bushy-branched above ; 

 the crowded leaves ascending. — Sandy or gravelly soil, Md. and D. C, southw. 



66. P. xanthophysum Gray. Yellowish green ; culms ascending, in small tufts, 

 2-6 dm. high, scabrous; sheaths loose, at least the lower overlapping, sparsely 

 papillose-pilose, bearded at the summit ; ligule minute ; blades erect or nearly so, 

 rather thin, strongly nerved, 1-1.5 dm. long, 1-1.8 cm. wide, narrowed to the 

 TOvmAedi ciliate base, otherwise glabrous; panicle finally long-exserted, 0.5-1.2 

 dm. long, very narrow, few-flowered, the branches erect; spikelets 4 mm. long, 

 broadly obovate, very turgid, pubescent, rarely glabrous ; first glume nearly \ as 

 long as the spikelet, pointed, second scarcely covering the fruit. Branching in 

 midsummer from the second and third nodes, branches erect, mostly sini]ile ; 

 the large erect leaves making the plant appear very leafy in the middle. — Dry 

 soil. Me. to Man., and Pa. 



67. P. Wilcoxianum Vasey. Culms erect, 1-2 dm. high, copiously papillose- 

 pilose as are the usually overlapping sheaths (rarely nearly glabrous) ; ligule 

 about 1 mm. long; blades erect, 5-6.5 cm. long, 3-5 mm. wide, densely long- 

 pilose on both surfaces; panicle finally exserted, 2-4 cm. long, about half as 

 vnde, rather densely flowered, branches ascending; spikelets 2.7-3 mm. long, 

 oWong-obovate, pubescent ; first glume about i as long as the spikelet, second 

 hardly covering the fruit. Autumnal state branching from all the nodes, form- 

 ing bushy tufts with rigid erect leaves much overtopping the reduced panicles. — 

 Prairies, la. to S. Dak. and Kan. 



- 13. Scoparia. — Culms tall and stout, finally wide-spreading; blades flat, 

 elongated, not over 1.5 cm. wide; ligule short; spikelets abruptly pointed, 

 strongly 1-9-nerved. 



68. P. scoparium Lam. Grayish olive-green, velvety-pubescent all over except 

 as noted; culms 8-13 dm. high, erect or ascending, often geniculate at base, 



