GRASS FAMILY 97 



of the central spikelet 7 mm. long, smooth; awn of about the same length; lemma 

 of the lateral spikelets about 4 mm. long, acuminate or merely awn-pointed. 

 H. npdosum depressum Scribn. & Smith. Meadows: Wash. Ida. Calif. 

 Submont. My-Je. 



6. H. nodosum L. Tufted annual or perennial; stems 2-6 dm. high, erect 

 or sometimes decumbent at the base; leaf-blades 4-12 cm. long, 2-6 mm. wide, 

 scabrous; spike 3-8 cm. long; lemma of the central spikelet 6-8 mm. long; awn 

 6-12 mm. long; lemma of the lateral spikelets smaller. Meadows and waste 

 places: Alaska Calif. Tex. Yukon; Eu. Submont. Mont. Ap-Au, 



7. H. boreale Scribn. & Smith. Rather simple perennial; stem 3-10 dm. 

 high, lower sheaths often pubescent; leaf-blades 1-2.5 dm. long, 4-8 mm. wide, 

 scabrous; spikes 7-10 cm. long; lemma of the central spikelet scabrous toward 

 the apex; awn about 1 cm. long; lemma of the lateral spikelets about 6 mm. 

 long, subulate-pointed. Meadows: Alaska Calif. Ida. Colo. (?) Submont. 

 Je-Jl. 



8. H. caespitosum Scribn. Cespitose perennial; stem 3-6 dm. high, 

 smooth; leaf-blades 5-15 cm. long, 3-5 mm. wide; spike 3-5 cm. long; lemma of 

 the central spikelet lanceolate, 6 mm. long; awn about 12 mm. long; lemma of 

 the lateral spikelets 2-4 mm. long, with an awn of about the same length. Mead- 

 ows and springy places: Sask. S.D. Kans. N.M. Ida. Wash. Plain 

 Submont. Je-Au. 



9. H. jubatum L. Tufted perennial; stem 2-8 dm. high, erect; leaf-blades 

 3-12 cm. long, 2-4 mm. wide, scabrous; spikes 5-10 cm. long; lemma of the 

 central spikelet 6-8 mm. long, scabrous at the apex; awn 4-6 cm. long; lemma 

 of the lateral spikelets 4-6 mm. long, short-awned. Dry sandy soil and prairies: 

 Lab. N.J. Tex. Calif. Alaska. Plain Subalp. Je-S. 



10. H. montanense Scribn. Erect biennial or perennial; stem 6-10 dm. 

 high, smooth; spike 5-7 cm. long; leaf -blades 5-10 cm. long, 4-6 mm. wide, 

 scabrous; central spikelets usually 2-flowered; lemma of the first flower about 1 

 cm. long, lanceolate, scabrous; awn 16-18 mm. long; lemma of the second flower 

 with the awn 12-14 mm. long; lateral spikelets similar to the central one, but 

 the second flower rudimentary. Meadows: Mont. Submont. 



11. H. murinum L. Tufted perennial; stem 2-6 dm. high, erect or de- 

 cumbent at the base; leaves 3-15 cm. long, 2-6 mm. wide, scabrous; spikes 5-10 

 cm. long; empty glumes of the central spikelet lance-subulate; outer glumes 

 of the lateral spikelets setaceous and merely scabrous; awns 18-25 mm. long; 

 lemma 10-12 mm. long, scabrous toward the apex; awns about 25 mm. long. 

 Ballast and waste places: Calif. B.C. Ida. N.M. ; also along the eastern 

 coast: N.Y. D.C.; adv. and nat. from Eu. Son. Submont. My-Au. 



76. SITANION Raf. 



Tufted perennials, with cylindric, spicate inflorescence. Spikelets sessile, 

 several at each node of the articulate rachis, 1-5-flowered. Empty glumes 2, 

 rarely entire, awn-like, usually 2-5-cleft with subulate awned divisions. Lemma 

 broader, entire, long-awned, or 2- or 3-cleft and short-awned. Palet shorter 

 than the glume, 2-keeled. Styles very short, distinct; stigmas plumose. 



Empty glumes lanceolate, scarious-margined. 



Leaf-blades not white-margined. 1- S. lanceolatum. 



Leaf-blades white-margined. 2. 5. marginatum. 



Empty glumes setaceous, or cleft into setaceous divisions, not scarious-margined. 

 Empty glumes setaceous, entire; lowest flower perfect. 



Lemma soft-pubescent. 3. S. pubiflorum. 



Lemma glabrous. . 4. S. elymoides. 



Empty glumes or some of them 2-cleft; lowest flower rudimentary. 

 Lemma pubescent; sheaths and blades densely pubescent. 

 Blades and sheaths short-hairy, subvelutinous. 



Awns at least 4 times as long as the lemma. 5. S. Hystnx. 



Awns 2-3 times as long as the lemma. 6. S. cmereum. 



Blades and sheaths long-hairy. 7. S. cihatum. 



Lemma glabrous or scabrous. 



Empty glumes subulate-lanceolate, bifid about two-thirds their length. 



8. O. ITlSMldTC, 



