GRAMINEAE. 99 



31. MUHLENBERGIA Schreb. 



Mostly perennial grasses, with flat or convolute leaves and paniculate inflores- 

 cence. Rootstocks often scaly. Spikelets I -flowered, very rarely 2-flowered. 

 Scales 3, very rarely 4; the outer ones empty, membranous or hyaline, acute and 

 sometimes awned; third scale 3-5 -nerved, subtending a paletand perfect flower, ob- 

 tuse, acute, or very often produced into a capillary awn; palet 2-keeled. Stamens 

 often 3. Styles distinct. Stigmas plumose. Callus minute. Grain narrow, free, 

 tightly enclosed in the scale. [In honor of Henry Muhlenberg, 1756-1817, North 

 American botanist.] About 60 species, chiefly natives of America, a few Asiatic. 



Panicle contracted, narrow, spike-like, the short branches rarely spreading. 

 Flowering scales not awned but sometimes awn-pointed. 



Outer scales not awned, about half as long as the flowering scale, acute. 



I. M, sobolifera. 

 Outer scales long-acuminate, awn-pointed or awned. 



Outer scales about equal in length to the flowering scale, sharp-pointed, 



about 3 mm. long. 2. M. Mexicana. 



Outer scales exceeding the flowering scale, generally twice its length, awned, 



about 5 mm. long. 3. M. racemosa. 



Flowering scale long awned; awn usually twice the length of the scale, sometimes 



shorter. 

 Outer scales about equalling the flowering scale. 



Basal hairs not more than one-half the length of the flowering scale. 



Spikelets consisting of 3 scales and i perfect flower. 4, M. sylvatica. 

 Spikelets consisting of 4 scales, the third with a perfect flower, the 



fourth empty and awned. 5. M. ambigua. 



Basal hairs as long as the flowering scale. 6. M. comata. 



Outer scales one-half to two-thirds as long as the flowering scale. 



7. M. tenuiflora. 

 Outer scales less than one-third the length of the flowering scale. 



First scale minute, often wanting; flowering scale with an awn less than 



twice its length. 8. M. diffusa. 



First scale about two-thirds as long as the second. 



Panicle contracted, its branches closely appressed ; awn about three 



times as long as the flowering scale. 9. M. palustris. 



Panicle open, its branches finally spreading; awn four times or more 

 as long as the flowering scale. 10. M. microsperma. 



Panicle open, its branches long and spreading. 



Culms 4.5 dm. tall or more; panicle diffuse; leaves elongated, not rigid. 



ii. M. capillaris. 

 Culms 3 dm. tall or less; leaves 5 cm. long or less, rigid. 



Secondary branches of the panicle single; basal leaves short, numerous, strongly 



recurved. 12. M. gracillima. 



Secondary branches of the panicle fascicled; basal leaves few, not recurved. 



13. M. pungens, 



1. Muhlenbergia sobolifera (Muhl.) Trin. ROCK MUHLENBERGIA. (I. F. f. 

 320.) Glabrous; culms 3-9 dm. tall, erect, slender, simple, or sparingly branched 

 above, smooth. Leaves rough, those of the culm 1-1.5 dm. long, 2-6 mm. wide, 

 those of the branches 2.5-7.5 cm. long, about 2 mm. wide; panicle 7 5-15 cm. in 

 length, slender, its branches 1.8-2.5 cm. l n g; outer scales about I mm. long, half 

 to two-thirds the length of the spikelet; the third scale scabrous, obtuse, 3-nerved, 

 the middle nerve usually excurrent as a short tip. Rocky woods, N. H. and 

 Mass, to Minn., south to Va., Tenn. and the Ind. Terr. Sept. -Oct. 



2. Muhlenbergia Mexicana (L.) Trin. MEADOW MUHLENBERGIA. (I. F. f. 

 321.) Glabrous; culms 6-12 dm. long, erect, or often prostrate, much branched, 

 smooth. Leaves scabrous, those of the culm 1-1.5 dm. long, 2-6 mm. wide, the 

 branch leaves smaller; panicle 5-15 cm. long, contracted, its branches spike-like, 

 2.5-5 cm - l n g> erector appressed; spikelets 2.5-3 mm. long; outer scales some- 

 what unequal, exceeding the flowering one, or slightly shorter, acuminate or short- 

 awned, scabrous, especially on the keel ; third scale acuminate, scabrous, particu- 

 larly toward the apex. In swamps and borders of fields, N. B. to western Ont., 

 south to N. Car., Tenn., Neb. and the Ind. Terr. Aug. -Sept. 



2- ?* "'ilenbergia racemosa (Michx.) B. S. P. MARSH MUHLENBERGIA. (I. 

 F. f. $2...) Culms 3-9 dm. tall, erect, usually m^ch branched, smooth and 



