65 



j Fig. 43. Muhlenbergia sylvatica Torr. WOODLAND DROP-SEED.— a, b, 

 i Spikelets; c, the same with the outer or empty glumes removed. Other species 

 of Muhlenbergia are illustrated by Figs. 99 to 111, in Bui. 7, and 443 to 449, in 

 1 Bui. 17. 



43. MTJITLENBERGIA Schreb. Gen. PL 44. 1789. Spikelets 1-flowered, her- 

 maphrodite; rachilla articulated above the empty glumes, forming a very short 

 and usually hairy callus below the floral glume, but not extending beyond it. 

 Glumes 3, the first two empty, membranaceous or hyaline, 1- to 3-nerved or 

 nerveless, usually unequal and shorter than the floral glume, acute, mucronate- 

 pointed or sometimes awned; 3d or flowering glume narrow, smooth, or more 

 or less pilose below, 3- to 5-nerved, awned from the acute apex, or from between 

 the teeth of the more or less conspicuously bidentate apex. Awn straight or 

 flexuose. Palea thin, 2-nerved, usually about the length of its glume. Stamens 

 3. Styles distinct. Grain closely enveloped by the fruiting glume. Perennial 

 grasses (rarely annual) with small spikelets and greatly varying habit; culms 

 a few inches to several feet high, simple or much-branched; leaves long or short, 

 flat or strongly involute; panicle narrow and spike-like or open and widely 

 spreading. Formerly included in Agrostis. 



Species about 60, chiefly American; most abundant in Mexico 



15444— No. 20 5 



