48 POACEAE 



thick; empty glumes ovate, obtuse, or abruptly acute, about 1 mm. long; lemma 

 2.5-3 mm. long, long-acuminate. Vilfn Richardsoniis Trin. Prairies and meadows: 

 Que.— Me.— X.M.— Calif.— B.C. Plain—Mont. Je-S. 



10. M. simplex (Scribn.) Rydb. Ce.spitose leafy annual; stem 5-15 cm. high, 

 smooth, with short lower internodes; leaf-blades 1-4 cm. long, 1-2 mm. broad, 

 scabrous on the margins and nerves above; panicle 2-5 cm. long, 2-4 mm. thick; 

 empty glumes less than 1 mm. long, ovate, obtuse or truncate; lemma 3-nerved, 

 mucronate, scabrous above, 2-2.3 mm. long. Sporobolus simplex Scribn. Wet 

 places: Neb. — "SM. — Mont. Plain^Mont. Au-S.- 



11. M. filiformis (Thurb.) Rydb. Cespitose annual; stem 7-30 cm. high, 

 slender, filiform, glabrous; leaf-blades 1-2 cm. long, 0.5 mm. wide or less, usually 

 flat, scabrous above; panicle long-exserted, narrow, lax, 2-10 cm. long, more than 

 2 mm. thick; empty glumes less than 1 mm. long, ovate, obtuse, 1-nerved, mucron- 

 ate; lemma 2 mm. long, lanceolate, acuminate. Vilfn depauperatn filiformis 

 Thurb. V. graciliima Thurb. Wet places: Mont. — Colo. — Calif. — B.C. Sub- 

 mont. — Suhalp. My-Au. 



12. M. aristata Rydb. Cespitose annual; stems usually only 4-6 cm. high; 

 leaf-blades 8-14 mm. long, and about 1 mm. wide; panicle few-flowered, very 

 narrow, with short erect branches; empty glumes 1-1.25 mm. long, ovate, 

 acutish or obtuse and somewhat erose at the apex; lemma about 2.5 mm. long, 

 strongly veined. Sporobolus aristatus Rydb. Wet places: Utah — Wyo. — Colo. 

 Submont. Jl-Au. 



13. M. Wolfii (Vasey) Rydb. Cespitose annual; stem 2-5 cm. high; lower 

 sheaths inflated, glabrous; leaf-blades rarely over 1 cm. long, strongly nerved; 

 panicle spike-hke, about 1 cm. long, scarcely 2 mm. thick, lax; empty glumes 

 ovate, about 0.5 mm. long; lemma ovate, acute, about 1 mm. long. Sporobolus 

 Wolfii Vasey. Wet places: Colo. — Ariz. Mont. — Subnlp. 



14. M. pauciflora Buckl. Perennial; stems tufted, wiry, erect, 3-5 dm. 

 high, scabrous, leafy; leaf -blades narrow, involute, 5-15 cm. long, minutely 

 scabrous; panicle 10-15 cm. long; spikelets nearly sessile; empty glumes sub- 

 equal, lanceolate, usually awn-pointed, 2 mm. long; lemma 3-nerved, lanceolate, 

 acuminate, 3-4 mm. long, scabrous on the keel; awn 8-12 mm. long. Rocky 

 hills: Tex.— Colo.— Utah— Mex. Son. My-S. 



15. M. polycaulis Scribn. Perennial, fasciculate-branched at the base; 

 stems ascending or erect, leafy, glabrous or minutely scabrous; leaf-blades erect, 

 2-6 cm. long, 1-2 mm. wide, often involute; panicle 5-10 cm. long, narrow; 

 rachis scabrous, triangular; pedicels scabrous, short; empty glumes subequal, 

 broadly lanceolate, acute or awm-pointed; lemma broadly lanceolate; awn 1-2.5 

 cm. long. Dry ledges and in canons: Tex. — ^se Utah — IVIex. Son. Au-S. 



16. M. curtifolia Scribn. Perennial, fasciculate-branched at the base; 

 leaf-blades 1-2.5 cm. long, 2 mm. wide or less, pungent at the end; panicle nar- 

 row, 4-8 cm. long; branches erect; rachis triangular or compressed, scabrous; 

 empty glumes lanceolate, acute, subequal, 2.5 mm. long, scabrous along the 

 keel; lemma broadly lanceolate; awn scabrous, 1-3 mm. long. Canons: 

 s Utah. Son. Au. 



17. M. gracilis (H.B.K.) Trin. Tufted perennial; stems 3-6 dm. high, 

 erect; leaf-blades often convolute, 5-20 cm. long; i)anicle narrow but ratiier 

 loose; branches erect, flowering to the base; emijtj- glumes unequal, the first 2 

 mm. long, l-nerved, acute; lemma without the awn about 4 mm. long, scabrous 

 on the back, ciliate on the margins. M. Irijida Woot. & Standi, not Hack. 

 Mountains: Tex.— Colo. — Calif.; Mex. Son. — Mont. J^S. 



18. M. subalpina Vasey. Tufted perermial; stem erect, 1-3 dm. high; 

 leaf-blades usually involute, 2-7 cm. long; i)anicle narrow, dense; branches erect, 

 less than 1 cm. long; first empty glume about 2 mm. long, acute, 1-nerved, awn- 

 pointed; lemma 3-3.5 mm. long. M. gracilis breviaristntn \'asey. Dry ridges: 

 Wyo. — X.M. M out. ^Submont. .Il-Au. 



19. M. filiculmis Vasey. Tufted perennial; stem erect, filiform, 1-2.5 dm. 

 high, leafy at the base; leaf-blades filiform, 2-4 cm. long, involute: jianirde spike- 



