MANUAL OF THE GRASSES OF THE UNITED STATES 371 



Pedicels capillary, elongate. 



Panicles very diffuse; pedicels straight; glumes glabrous 3. M. fragilis. 



Panicles open but scarcely diffuse; glumes pilose. 



Pedicels sinuous and tangled; glumes long-pilose 4. M. sinttosa. 



Pedicels straight or subflexuous; glumes minutely pilose.... 2. M. minutissima. 

 Pedicels short, appressed; glumes glabrous. 



Panicles loose, delicate; spikelets 1 to 1.2 mm. long 1. M. wolfii. 



Panicles narrow, contracted; spikelets 2 mm. long 13. M. filiformis. 



Culms simple, compressed 29. M. uniflora. 



lb. Plants perennial. 

 3a. Rhizomes developed, usually prominent, scaly, creeping, often branching. 

 4a. Blades 2 mm. wide or less, mostly short and involute. 

 5a. Panicles open, the spikelets on slender pedicels. 



Spikeless awned, 4 to 5 mm. long; blades involute. Panicle branches in stiffly 



spreading fascicles. 50. M. pungens. 



Spikelets awnless, acutish or mucronate, 1 to 2 mm. long; blades flat. 

 Sheaths compressed keeled; panicle oblong; eastern species. 



28. M. TORREYANA. 



Sheaths rounded; panicle as broad as long; western species. 



Ligule 1 to 2 mm. long, auricled 26. M. arenacea. 



Ligule minute, not auricled 27. M. asperifolia. 



5b. Panicles narrow, more or less condensed, the spikelets on short pedicels. 



Culms tall, stout, somewhat woody at base, as much as 6 mm. thick, 1 to 3 m. tall. 



30. M. DUMOSA. 

 Culms lower, slender. 

 Lemma and palea glabrous. 



Culms smooth, widely creeping, the blades fine, conspicuously recurved, 

 spreading. 



Spikelets about 3 mm. long 14. M. repens. 



Spikelets about 2 mm. long 15. M. tjtjlis. 



Culms nodulose-roughened, erect or decumbent at base, sometimes soreading, 



but not widely creeping 16. M. richardsonis. 



Lemma and palea pilose or villous on the lower half. 

 Awns 6 to 10 mm. long. 



Panicles densely flowered; glumes as long as the floret. 



21. M. POLYCAULIS. 



Panicles loosely flowered; glumes about half as long as the floret. 



23. M. ARSENEI. 

 Awns 1 to 3 mm. long or the lemma mucronate only. 



Blades 5 to 10 cm., rarely 15 cm. long, flat 20. M. glauca. 



Blades 1 to 3 cm. long, involute or pungently pointed. 



Glumes about half as long as the floret; lemma 2 to 2.5 mm. long. 



17. M. VILLOSA. 

 Glumes nearly as long as the floret; lemma 3 to 4 mm. long. 



Culms glabrous below the nodes; sheaths glabrous (rarely pubescent 

 below the summit); ligule 1 mm. long, short lacerate; lemma 

 loosely villous on the margins on lower half and at the very base, 



mucronate to short awned 18. M. thurberi. 



Culms strigose below the nodes; sheaths often strigose to hirsute; 

 ligule 0.5 to 1 mm. long; lemma densely villous on lower half; 



awn 1 to 3 mm. long 19. M. curtifolia. 



4b. Blades flat, at least some of them more than 3 mm., usually 5 mm. wide or more. 

 6a. Panicles loosely flowered, slender, much exceeding the leaves (see also M. sylva- 

 tica) ; glumes broad below, abruptly pointed, shorter than the body of the lemma. 

 Culms slender, rather weak, becoming much branched, glabrous or slightly sca- 

 brous below the nodes. Lemma acuminate, 2.5 to 3.5 mm. long, awned. 



37. M. BRACHYPHYLLA. 



Culms erect, simple or sparingly branched. 



Spikelets 1.5 to 2.5 mm. long; lemma awnless or awn-tipped; blades commonly 



not more than 5 to 7 mm. wide. 35. M. sobolifera. 



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 36. M. tenuiflora. 



6b. Panicles usually densely flowered (sometimes loose in M. sylvatica); glumes 

 tapering from base to apex. Culms commonly freely branching (often simple or 

 nearly so in M. glomerata). 

 Hairs at base of floret copious, as long as the body of the lemma.... 31. M. andina. 

 Hairs at base of floret inconspicuous, not more than half as long as the lemma. 



