GRAMINEAE (GRASS FAMILY) 115 



profusely from the upper, the short branches aggregated at the summit; the, 

 crowded leaves widely spreading. (P. pauciflorum Ell., not R. Br.) Sandy 

 soil, Del. to 1). C., and south w. ; and in n. 1ml., near L. Michigan. 



ti::. P. Scribneriinum 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 66 - p S cr >neri. 

 Tex. FIG. 66. f num - 8 P |ke " 



64. P. LeibSrgii (Vasey) Scribn. Culms 3-8 dm. high, 



scabrous, at least below the nodes ; sheaths strongly papillose-hispid, with 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 J 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, 8-16 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 

 rounded 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 J as 

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

 midsummer from the second and third nodes, branches erect, mostly simple ; 

 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 

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

 oblong-obovate, pubescent ; first glume about 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. 



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

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

 stronr/ly 7-9-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, 



