GRASS FAMILY 95 



flowered; lemma acuminate or awn-pointed, scabrous, about 1 cm. long. Prair- 

 ies and river valleys: Neb. Tex. Ariz. B.C. Plain Mont. Je-S. 



18. A. riparium Scribn. & Smith. Stem glabrous, erect, 4-6 dm. high; 

 leaf-blades flat, becoming involute, 5-15 cm. long, 2-4 mm. wide, scabrous 

 throughout; spike 5-10 cm. long; spikelets 8-15, compressed, 5-7-flowered, 

 spreading, 5-6 mm. long; lemma oblong-lanceolate, acute, scabrous towards 

 the apex, acute or acuminate. River banks: Mont. Colo. Submont. 



19. A. Smithii Rydb. Stem 3-10 dm. high; leaf-blades spreading, rigid, 

 bluish green, glaucous, smooth or minutely scabrous beneath, becoming involute, 

 1-3 dm. long, 4-6 mm. wide; spikes 7-18 cm. long; spikelets 7-13-flowered, some- 

 times in pairs; lemma 8-12 mm. long, lanceolate, acute or acuminate, seldom 

 awn-pointed, smooth or nearly so. A. spicatum Scribn. & Smith, in par.t. A 

 occidentale Scribn. BLUE-JOINT; BLUE-STEM. Prairies and plains: Man. Mo 

 Tex. Ariz. Ore. B.C. PlainMont. Je-S. 



20. A. molle (Scribn. & Smith) Rydb. Stems 4-8 dm. high; leaf-blades 

 more or less glaucous, 1-3 dm. long, 2-4 mm. wide, at last involute, scabrous; 

 spike 1-2 dm. long, rather dense; spikelets about 2 cm. long, 6-8-flpwered; 

 lemma 8-10 mm. long, densely hispidulous. River bottoms, especially in alka- 

 line soil: Sask. N.M. Utah Wash. Plain Mont. Jl-S. 



21. A. lanceolatum Scribn. & Smith. Stem 6-10 dm. high, smooth and 

 shining; leaf-blades acuminate, 12-30 cm. long, 4-6 mm. wide, flat, scabrous 

 beneath, pilose above; spike 1-2 dm. long; spikelets 10-20 mm. long, 4-7-flowered, 

 erect; lemma 8-15 mm. long, broadly lanceolate, more or less short-pubescent. 

 Banks and meadows: Wash. Ida. Ore. Je-Jl. 



22. A. subvillosum (Hook.) E. Nelson. Stems 4-6 dm. high, slender, 

 glabrous; leaf -blades 1-2 dm. long, 2-4 mm. wide, flat or at last involute, scab- 

 rous; spike rather crowded; spikelets compressed, 12-15 mm. long; lemma 6-10 

 mm. long, obtuse or acute. River banks and sandy soil: Sask. Neb. Colo. 

 Nev. B.C. Plain Mont. Je-Au. 



23. A. dasystachyum (Hook.) Scribn. Stem 3-10 dm. high; leaf-blades 

 5-20 cm. long, 2-6 mm. wide, flat, becoming involute in drying; spike 6-18 cm. 

 long; spikelets slightly compressed, 4-8-flowered; lemma broadly lanceolate, 10- 

 12 mm. long, acute or rarely short-awned. Sand-dunes: Hudson Bay Mich. 

 Wis. Ida. Sask. Plain Boreal. Jl-Au. 



73. TRITICUM L. WHEAT. 



Annuals or biennials with spicate inflorescence. Spikelets solitary at each 

 ' node, alternate, 2-5-flowered; flowers mostly perfect. Empty glumes with 

 one edge towards the rachis, broad, short, often toothed, but seldom awned at 

 the apex. Lemma ventricose on the back, several-nerved, often awned or at 

 least toothed at the apex. Palet shorter than the lemma, 2-keeled. Grain 

 deeply furrowed, free, pubescent at the apex. 



Empty glumes distinctly keeled only at the apex; grain dull, neither glossy nor semi- 

 translucent. I- T. aestivum. 



Empty glumes distinctly keeled, almost winged, to the base; grain glossy, often some- 

 what translucent. 2. T. durum. 



1. T. aestivum L. Annual or biennial; stem about 1 m. high, hollow, 

 smooth; leaves at first rather light green, soft; spike 4-12 cm. long, 4-angled; 

 spikelets mostly 4-flowered; lemma with or without awn. T. sativum Lam. 

 WHEAT. Old fields and waste places: cult, and rarely escaped. 



2. T. durum Desf. Annual or rarely biennial; stem 1 m. high or more, 

 usually with a pith; leaves smooth, whitish green, with hard cuticle; spike almost 

 terete, thicker than in the ordinary wheat, 5-10 cm. long; lemma long-awned. 

 DURUM or MACARONI WHEAT. Old fields and waste places: cult, and rarely 

 escaped. 



74. SECALE L. RYE. 



Annuals or biennials, with spicate inflorescence. Spikelets solitary at each 

 node, alternate, 2-flowered. Flowers all hermaphrodite and fertile. Empty 

 glumes subulate, awn-pointed, with one edge towards the rachis. Lemma long- 



