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. TENtTIFLORA. 



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. 



uniflora). 



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

 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. EMERSLEYI. 



Lemma glabrous or obscurely pubescent. 

 Lower sheaths compressed-keeled. 



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

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



35. M. VIRESCENS. 



