MANUAL OF THE GRASSES OF THE UNITED STATES 359 



Spikelets 3 to 4 mm long; lemma with an awn 2 to 5 times as 

 long as the body; blades commonly 8 mm or more wide. 



23. M. TENTJIFLORA. 



7b. Panicles usually densely flowered (sometimes loosely in M. 

 sylvatica) ; culms commonly freely branching (sparingly so or 

 even simple in M. racemosa) ; blades mostly not more than 5 

 mm wide, usually ascending; glumes tapering from base to 

 apex. 

 Glumes with stiff awn-tips, much exceeding the awnless lemma; 

 panicles terminal on the culm or leafy branches, compact, 



interrupted, bristly 25. M. racemosa. 



Glumes acuminate, sometimes awn-tipped but not stiff and 

 exceeding the lemma; panicles terminal and axillary, numer- 

 ous, not bristly. 

 Culms glabrous below the nodes; panicles not compact, the 

 branches ascending; plants sprawling-topheavy, the 



branchlets geniculate-spreading 26. M. mexicana. 



Culms strigose below the nodes; panicles compact or if not the 

 branches erect or nearly so; plants often bushy-branching 

 but not sprawling with geniculate branchlets. 

 Callus hairs wanting; lemma nearly smooth, awnless. 



27. M. GLABRIFLORA. 



Callus hairs present; lemma pubescent below. 



Panicles not compactly flowered; lemma with awn as 

 much as 10 mm or more long (sometimes awnless) ; 

 some of the blades 10 to 15 cm or more long. 



28. M. SYLVATICA. 



Panicles compactly flowered or, if not, lemma awnless; 

 blades commonly less than 10 cm long, but some- 

 times longer. 



Sheaths glabrous 29. M. foliosa. 



Sheaths scabrous 21. M. californica. 



2b. Creeping rhizomes wanting, the culms tufted, usually erect (see also M. 

 uni flora) . 

 8a. Second glume 3-toothed (rarely not toothed in M. filicuJmis). 

 Lemma 2.5 to 3 mm long; culms filiform, 10 to 20 cm tall. 



17. M. FILICULMIS. 



Lemma 4 mm long; culms stouter, 30 to 60 cm tall 34. M. Montana. 



8b. Second glume usually acute or awned, sometimes erose-toothed, not 

 distinctly 3-toothed. 

 9a. Panicle narrow or spikelike, the branches floriferous from the base or 

 nearly so ( see also M. metcalfei). 

 Lemma acuminate, mucronate or short-awned. 

 Blades involute. 



Panicle elongate and spikelike 55. M. rigens. 



Panicle narrow but scarcely spikelike, the branches loosely flowered. 

 Blades mostly in a short basal cluster; panicle 5 to 8 cm. long. 



33. M. jonesii. 

 Blades not in a short basal cluster; panicle 10 to 30 cm long. 



45. M. DUBIA. 

 Blades flat, folded, or loosely involute. 

 Panicle more or less spikelike. 



Culms delicate; ligule about 2 mm long 4. M. filiformis. 



Culms wiry; ligule minute. 



Panicle slender, rather loosely flowered.. 10. M. cuspidata. 

 Panicle dense, interrupted, the branches closely flowered. 



11. M. WRIGHTII. 



Panicle narrow but not spikelike. 



Lemma villous below 54. M. emersleti. 



Lemma glabrous or obscurely pubescent. 

 Lower sheaths compressed-keeled. 



Glumes about as long as the floret-. 52. M. lindheimeri. 

 Glumes distinctly shorter than the floret. 



53. M. INVOLUTA. 



Lower sheaths not compressed 51. M. longiligtjla. 



Lemma with an awn as much as 5 mm long. 



Old sheaths becoming flat and more or less coiled at base of plant. 



35. M. virescens. 



