POACEAE. 33 



spikelets above the middle; spikelets nodding, 15-20 ram. long, rather dense; 

 lemma lanceolate, pubescent, 11-13 mm. long, the awn 13-15 mm. long. 

 Sparingly introduced in waste places. 



Bromus sterilis L. Annual, the stout stems 50-100 cm. high, usually 

 decumbent at base; panicle 10-20 cm. long, loose and drooping, its branches 

 in whorls of 2-6, long and slender, usually bearing but one spikelet; spikelets 

 drooping, 2.5-3.5 cm. long, 6-10-flowered; lemma narrowly lanceolate, 17-20 

 mm. long, bearing a stout rough awn, 20-30 mm. long. In waste places, 

 infrequent. 



Bromus maximus Desf. Stems 20-40 cm. high; sheaths and blades pilose; 

 panicle erect, 5-10 cm. long, somewhat one-sided, the branches rather short 

 and erect or nearly so after flowering. Sparingly introduced from Europe. 



Bromus brizaeformis Fisch. & Mey. Annual, erect, 30-60 cm. tall; leaf 

 blades pubescent; panicle 5-25 cm. long, loose, one-sided, nodding; spikelets 

 15-25 mm. long, elliptical, compressed; lemmas very broad, smooth, awnless, 

 or the uppermost with short awns, 1-2 cm. long. Introduced and becoming 

 abundant. 



Bromus hordeaceus L. Annual, erec':, 20-60 cm. tall; leaf blades pilose 

 or smooth, the sheaths pubescent with retrorse hairs; panicle narrow, dense, 

 5-10 cm. long; spikelets erect, 12-15 mm. long, 5-12-flowered; lemma pu- 

 bescent, bearing a stout straight or somewha.t twisted awn 6-9 mm. long. 

 Very common. 



Bromus hordeaceus glabrescens (Coss.) Shear. Spikelets smooth or 

 nearly so. Very common. 



Bromus secalinus L. Annual, erect, 30-70 cm. tall; leaf blades 10-20 cm. 

 long, sparsely hairy above, smooth beneath; sheaths glabrous; panicle 8-18 

 cm. long, pyramidal, erect at first, in fruit somewhat drooping; spikelets 

 oblong-lanceolate, turgid in fruit, 10-18 mm. long; lemma glabrous or nearly 

 so, 6-8 mm. long, its margins involute in fruit, tipped with an awn 2-5 mm. 

 long; palea nearly equal to the lemma. Common in fields. 



Bromus commutatus Schrad. Very similar to B. secalinus; panicle more 

 drooping; lemma broader, not inroUed in fruit, tipped with a stout straight 

 awn 7-8 mm. long. Introduced from Europe. 



SS. DACTYLIS. 



Perennial grasses with flat leaves; inflorescence a densely 

 clustered or interrupted panicle; spikelets 3-5-flowered, short- 

 pedicelled, in small fascicles, the flowers all perfect or the upper 

 staminate; glumes thin, membranous, keeled, unequal, mucro- 

 nate; lemmas larger than the glumes, rigid, 5-nerved, keeled, 

 the midnerve extending into a point or short awn ; palea shorter 

 than the lemma; grain free, enclosed in the lemma and palea. 



Dactylis glomerata L. Orchardgrass. Perennial, tufted, the stout stems 

 60-150 cm. tall; leaf blades flat, scabrous, 6-8 mm. broad; sheath scabrous, 

 exceeding the internode; panicle 3-10 cm. long, pyramidal-ovate, greenish or 

 purplish; branches solitary, ascending, spikelet-bearing above; lemmas con- 

 spicuously ciliate on the keels. Escaped from cultivation. 



56. POA. Bluegrass. 



Annual or perennial grasses with simple stems and narrow 

 usually flat leaves; inflorescence a contracted or open panicle; 



4 



