GEAMINEAE 23 



Flowering glume not awneil. 



Lower glumes aonte. 1. M. sobolifera. 



Lower glumes strongly acuminate. 



Flowering glume \i'' or more long. 2. M. Mraricana. 



Flowering glume 1" or less long. 3. M. poliistaehya. 



Lower glumes exceeding flowering glumes. 4. M. racemosa. 

 Flowering glume awned. 



Lower glumes minute or wanting. 5. M. diffusa. 



Lower glumes J to f length of flowering glume. 6. M. tenuiflora. 



Lower glumes equalling flowering glume. 7. M. sylraiica. 



1. M. sobolifera (Muhl.) Trin. l°-3° high, erect: leaves 3'- 4' 

 long, 'i/'-W wide : panicle very slender, much-contracted, long-exserted, 

 2"- 6" long : spikeleta \" long. — Not uncommon in rooky woods. Sep- 

 tember-October. 



2. M. Mexicana (L. ) Trin. Much branching, lJ°-3° high, with 

 geniculate culms : panicles both lateral and terminal, contracted, with 

 appressed spike-like branches, more or less included : spikelets \\" or 

 more long ; hairs at base of flowering glume few, short : empty glumes 

 equal or very unequal, longer or shorter than the flowering glume. — 

 Common in low woods along streams. August-October. 



3. M. polystachya Mackenzie & Bush, n. sp. 2° high, erect, much 

 branched: leaves \\'-'i,\' long, l"-2" wide: panicles on peduncles 

 l'-5' long, long-exserted, 2'-4' long, densely flowered, the lower branch- 

 lets separated : flowers nearly sessile, \" long : the glumes as in the 

 last : hairs at base of flowering glume copious, J to J length of glume. — 

 Open rocky woods east of Sibley. August-October. 



4. M. racemosa (Michx.) B.S.P. Culms l°-3° high, usually much- 

 branched : panicle terminal, 2'- 4' long, usually dense and spike-like, 

 exserted, the branches very densely flowered. — Bogs and wet rocky 

 woods. Well distributed and rather common. August-October. 



5. M. tenuiflora (Willd. ) B.S.P. Distinguished from No. 7 only by 

 its shorter less acuminate, empty glumes.— Dry woods near Sibley. 

 A ugust-October. 



6. M. diffusa Willd. Nimble Will. Culms much-branched, dif- 

 fusely spreading or prostrate with numerous short leaves : panicles 

 slender and contracted, 2'-4' long, usually interrupted. — Often very 

 common in dry woods. August-October. 



7. M. sylvatioa Torr. Culms ascending, l°-3° high, bearing a con- 

 tracted panicle 3'- 6' long. — Common in low woods along the larger 

 streams. July-October. 



18. BRACHYELYTRUM Beauv. 



Perennial with erect, pubescent culms and one-flowered spikelets in 



simple panicles. Glumes three, the first two small and ineonspionous, 



the outer often wanting. Flowering glume hard, 5-nerved, hairy, long 



awn-pointed, together with the palet enclosing the grain. Palet as long 



