184 



GRAMINEAE. 



VOL. I. 



34. MUHLENBERGIA Schreb. ; Gmel. Syst. Nat. 2: 171. 1791. 

 [VASEYA Thurb. Proc. Acad. Phila. 1863: 79. 1863.] 



Mostly perennial grasses, with flat or convolute leaves and paniculate inflorescence. 

 Rootstocks often scaly. Spikelets i-flowered, very rarely 2-flo\vered. Scales 3, very rarely 

 4; the outer ones empty, membranous or hyaline, acute and sometimes awned; third scale 

 3~5-nerved, subtending a palet and perfect flower, obtuse, 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 

 .\Iuhlenberg, 1756-1817, North American botanist.] 



About 60 species, chiefly natives of America, a few Asiatic. Type species : Muhlenbcrgia 

 Schreberi Gmel. 



Panicle contracted, narrow, often slender, its branches erect or appressed. 

 Outer scales J4 as long as the flowering scale or less. 



First scale minute, often wanting ; flowering scale with an awn twice its length or less. 



1. M. Schreberi. 

 First scale about 2 /$ as long as the second ; flowering scale with an awn 3-4 times its length. 



2. M. palustris. 

 Outer scales more than y+ as long as the flowering scale. 



Plants with numerous and conspicuous rootstocks covered with short appressed scales. 

 Flowering scale awnless, or sometimes awn-pointed. 



Outer scales ovate to broadly lanceolate, cuspidate, about l / 2 as long as the flowering 

 scale. 3. M. sobolifera. 



Outer scales .subulate, equalling or exceeding the flowering scale, awn-pointed or awned. 

 Outer scales about equal in length to the flowering scale, about i l / 2 " long, sharp- 

 pointed. 4. M. mexicana. 

 Outer scales exceeding the flowering scale, generally twice its length, about 2}^" 

 long, awned. 5. M. racemosa. 

 Flowering scales long-awned, the awn usually twice as long as the scale, sometimes 



shorter. 



Outer scales y^-% as long as the flowering scale, ovate to broadly lanceolate, cuspidate. 



6. M. tenuiflora. 

 Outer scales equalling the flowering scale, subulate. 



Basal hairs not more than l / 2 as long as the flowering scale. 



Spikelets consisting of 3 scales and i perfect flower. 7. M. umbrosa. 



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



empty and awned. 8. M. ambigua. 



Basal hairs as long as the flowering scale. 9. M. comata. 



Plants without rootstocks, or these rarely present and with few scattered long scales. 



Annual ; outer scales less than l / 2 as long as the spikelet, rounded or truncate at the 



erose apex. 10. M. simplex. 



Perennial ; outer scales l / 2 as long as the spikelet or more, acute or acuminate. 



Culms simple at the base, finally much-branched above; ligule about i" long, acutish ; 

 outer scales about l /2 as long as the spikelet, acute. n. M. brevifolia. 



Culms branched at the very base only, simple above ; ligule J4" long or less, erose- 

 truncate ; outer scales more than l / 2 as long as the flowering scale, attenuate. 



12. M. cuspidata. 

 Panicle open, its branches long and spreading, slender. 



Culms 1 6' tall or less, from much-branched rootstocks; blades 2' long or less. 



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



13. M. gracillima. 

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



14. M. pungcns. 

 Culms 20' tall or more; rootstocks none; blades elongated. 15. M. capillaris. 



i. Muhlenbergia Schreberi Gmel. Nimble Will. 

 Dropseed- or Wire-grass. Satin-grass. Fig. 439. 



M. Schreberi Gmel. Syst. Nat. 2: 171. 1791. 

 M. diffusa Willd. Sp. PI. i : 320. 1 798. 



Glabrous, culms i-3 long, decumbent, or often pros- 

 trate or creeping and ascending, very slender, diffusely 

 branched. Sheaths shorter than the internodes, loose; 

 ligule short, fringed; blades il'-3l' long, \"-2" wide, 

 scabrous ; panicle 2'-8' long, slender, somewhat lax, its 

 branches i'-2' long, erect; outer scales of the spikelet 

 minute, the lower one often wanting; the third scale, 

 exclusive of the awn, about i" long, strongly scabrous, 

 particularly upon the nerves ; the awn i"-2" in length. 



On dry hills and in woods and waste places, Maine to 

 Minnesota, south to Florida and Texas. Aug.-Sept. 



