18 POACEAE. 



pubescent. — S., especially along the Susquehanna. Rather rare in woods. — 

 Schists. — Sum. and fall. 



22. P. Ashei G. Pearson. Stems tufted, 2-4 dm. tall, erect, usually sparingly 

 branched, rarely much branched and prostrate, puberulent: leaf -blades lanceo- 

 late, sparsely ciliate at the base, with long hairs, usually 5-8 cm. long, 6-10 mm, 

 ■vvide, a little cordate at the base, the upper blades about the same length, the 

 lower ones shorter, the early basal blades ciliate: panicle 5-7 cm. long: spike- 

 lets about 2.3 mm. long and about 1 mm. wide, elliptic. — Lower Susquehanna 

 valley. Bather rare, in woods. — Schists. — Sum. 



23. P. latifolium L. Stems 3-9 dm. tall, erect, simple, or somewhat branched 

 above: leaf -blades 7-18 cm. long, 2-4 cm. wide, cordate-clasping at the base, 

 acuminate, ciliate: panicle 8-15 cm. long: spikelets 3-4 mm. long, turgid, oval 

 to obovoid, pubescent. — Frequent, in woods. — Sum. 



24. P. clandestinum L. Stems tufted, 6-14 dm. tall, the branches clothed with 

 the papillose-hispid overlapping leaf -sheaths : leaf -blades ciliate at the cordate 

 and clasping base, the primary ones 1-2 dm. long, 1.5-2.5 cm. wide, acuminate, 

 lanceolate, those on the branches ovate-lanceolate and usually less than 1 dm. 

 long: primary panicle long-exserted, 9-12 cm. long, broadly ovate, the later 

 panicles wholly or partially concealed in the sheaths: spikelets 2.7-3 mm. long 

 and about 1.3 mm. wide, elliptic, pubescent with spreading hairs. — M. S. 

 Eather common, in moist soil. — Liinestones, schists. ■ — Sum. 



25. P, Boscii Poir. Stems tufted, erect, pubescent or glabrous, finally branch- 

 ing: leaf -sheaths glabrous, or softly pubescent; blades ovate-lanceolate, cordate 

 and clasping at the base, glabrous or pubescent, 6-12 cm. long, 2-4 cm. wide: 

 panicle 6-12 cm. long: spikelets 4-6 mm. long, 1.5-2 mm. wide, the scales dis- 

 tant, pubescent with long weak hairs. — Rather common, in woods. — Sum. 



9, CHAETOCHLOA Scribn. Annual or perennial grasses, with usually 

 flat, sometimes complanate, leaf-blades and dense terminal cylindric spike-like 

 or narrowly thyrsoid panicles. Spikelets with one or a cluster of 2-several 

 sterile barbed bristle-like persistent branches. Scales 4, the 3 outer membranous, 

 the first often very short and together with the larger second one empty, the 

 third scale frequently longer than the second, empty, or rarely enclosing a palet 

 and also sometimes a staminate flower, the fourth scale usually shorter than the 

 spikelet, chartaceous, glabrous, shining, often transversely rugose, finally indu- 

 rated, obtuse, enclosing a shorter palet of similar texture and a perfect flower. 

 Stamens 3. Styles distinct, elongate. Stigmas plumose. [Setaria Beauv., 

 not Achar.] — Foxtail. Foxtail-grass. 



Inflorescence with the spikelets racemosely arranged : bristles 5-16 at the base of 



each spikelet, involucrate. 1. C. (jlauca. 



Inflorescence with the spikelets in clusters or on branches : 

 bristles 1-3 at the base of each spikelet, not involucrate. 

 Bristles downwardly barbed. 2. C. verticillata. 



Bristles upwardly barbed. 



Panicle usually 1 cm. thick or less : bristles commonly 



green : spikelets about a mm. long. 3. C. viridis. 



Panicle usually 2-3 cm. thick : bristles usually purple : 



spikelets 2.5-3 mm. long. 4. C. italica. 



1, C. glauca (L.) Scribn. Stems tufted, 3-12 dm. tall: leaf -blades 1.5 dm, 

 long or less, 4-8 mm. wide, glaucous, at least the lower ones pilose near the 

 base on the upper surface: racemes dense, about 1 cm. in diameter, 2-10 cm, 

 long: spikelets broadly ovoid, 3 mm. long and 2 mm. wide, the acute flowering 

 scale striate, coarsely transversely rugose. — Common, in waste and cultivated 

 grounds. Nat. of Eu. — Sum. — Pigeon-grass. 



