POACEAE 159 



feet or wanting, the rachilla extending beyond the flowers as a long slender bristle or 

 sometimes bearing a narrow terminal scale. Scales 3 or 4, the 2 lower empty, awn-like, 

 subulate, lanceolate, or narrowly linear, rigid, persistent, the empty scales at each rachis- 

 node forming an apparent involucre and falling with the readily deciduous rachis joints, 

 the flowering scales lanceolate, rounded on the back, the nerves confluent into a straight or 

 divergent awn, or in the lateral spikelets awnless and sometimes much reduced ; palet 

 shorter than the scale, 2-keeled. Stamens 3. Styles very short, distinct. BARLEY. 



Each cluster of spikelets with all the empty scales bristle-like. 1. H. nodosum. 



Each cluster with four of the empty scales dilated above the base. 2. //. pusittum. 



1. Hordeum nodosum L. Stems 1.5-6 dm. tall, erect, or sometimes decumbent : 

 leaf-blades 4-13 cm. long, 2-6 mm. wide, flat, rough : spike 2.5-9 cm. long : spikelets us- 

 ually in 3's, the flowering scale of the central spikelet 6-8 mm. long, exclusive of the awn 

 which is 6-12 mm. long, the corresponding scale in the lateral spikelets much smaller and 

 short-stalked. [//. pratense Huds.] 



In meadows and waste places, Indiana to Minnesota, British Columbia, Alaska, Georgia, Texas 

 and California. Also in Europe and Asia. Summer. 



2. Hordeum pusillum Nutt. Stems 1-4 dm. tall, erect, or decumbent at the base : 

 leaf-blades 1-8 cm. long, 1-4 mm. wide, erect, rough above : spike 2.5-8 cm. long : spike- 

 lets usually in 3's, the scales awned, the empty ones rough, the flowering ones smooth, 

 that of the central spikelet 6-8 mm. long, short-awned, the corresponding scale in the 

 lateral spikelets smaller and very short-stalked. 



In dry soil, Ontario to British Columbia, Nebraska, Arkansas, Texas and California ; also sparingly 

 introduced into the southeastern United States. Summer. 



118. SITANION Kaf. 



Erect perennial grasses, with flat or involute leaf-blades and a terminal dense cylin- 

 dric spike which is covered with long spreading awns. Spikelets many, sessile, alternate, 

 at each joint of the articulated rachis, 1-5-flowered. Scales 3-7, the 2 lower empty, rarely 

 entire, usually 2-many-cleft, the divisions linear and long-awned, the awns spreading, the 

 flowering scales broader, acute, 'entire and long-awned, or 2-toothed and the teeth sometimes 

 short -awned ; palet shorter than the scale, 2-keeled. Stamens 3. Styles very short, dis- 

 tinct. 



1. Sitanion longifolium J. G. Smith. Stems 3-5 dm. tall, stout, glaucous : leaf- 

 blades of the innovations 1.5-3 dm. long, involute, often as long as the stems, those on the 

 stem 1-2 dm. long, 1-4 mm. wide : spike 1-1.5 dm. long, rather loosely flowered, its base 

 inclosed in the upper sheath : spikelets 2, or sometimes 3, at each node, the empty scales 

 subulate-setaceous, divaricate, 6-8 cm. long; flowering scales 8-11 mm. long, rough, 

 each tipped with a stout rough awn 5-6. 5 cm. long. 



In dry soil, Nebraska to Wyoming, Texas and Nevada. Summer. 



119. ELYMUS L. 



Usually tall perennial grasses, with flat or convolute often rigid leaf-blades and a 

 terminal cylindric dense spike which is sometimes interrupted and usually covered with 

 long awns. Spikelets numerous, sessile, crowded, usually in alternate pairs, sometimes in 

 3's or more, at each node of the continuous rachis, 2-several-flowered (rarely 1-flowered). 

 Scales 4-several (rarely 3), the 2 lower empty, rigid, awn-like, subulate, or linear, persis- 

 tent, awn-pointed or awned, those at each node forming an apparent involucre, the flower- 

 ing scales shorter, oblong to lanceolate, rounded on the back, obtuse or acute, usually 

 awned, rarely awnless, the remaining scales if any smaller and empty ; palet shorter than 

 the scale, 2-keeled. Stamens 3. Styles very short, distinct. Stigmas plumose. LYME 

 GRASS. WILD RYE. 



Empty scales narrowly awl-shaped : spike slender. 1. E. striatus. 



Empty scales linear-lanceolate to linear : spike stout. 



Flowering scales glabrous. 2. E. Virginicus. 



Flowering scales appressed-pubescent, usually densely so. 



Empty scales linear, thick, firm, each bearing generally an awn much 



shorter than the body, 3. E. hirsutiglumi*. 



Empty scales narrowly lanceolate, rather thin, each bearing commonly an 



awn equalling or exceeding the body. 

 Spike rather loosely flowered, nodding at the summit, usually long- 



exserted. 4. E. Canadensis. 



Spike densely flowered, compact, strict, usually included at the base. 5. E. robustus. 



