Brues—The Grasses of Milwaukee County. 
61 
KEY TO THE GENERA. 
Subfamily PANICOIDEAE. 
Tribe ANDROPOGONEAE. 
Inflorescence composed of spike-like silky racemes... ANDROPQGON. 
Infloresence paniculate; spikelets silky.SORGHUM. 
Tribe PANICEAE. 
1. Spikelets without an involucre of bristles.2, 
Spikelets with an involucre of bristles.4. 
2. Lemma leathery, indurated, with hyaline margins, not inrolled; 
spikelets lanceolate, forming slender spike-like racemes.. 
. DIGITARIA, 
Lemma chartaceous, indurated, margins inrolled, not hyaline.3. 
3. Glumes and lemmas awnless.PANICUM. 
Sterile lemma awned or pointed, inflorescence a panicle of crowded 
one-sided racemes. ECHINOCHLOA. 
4. Involucre consisting of one to many persistent bristles; spikelets 
in a dense cylindrical spike-like panicle.SET ARIA. 
Involucre consisting of two spine-bearing valves forming a bur. 
. CENCHRUS. 
Subfamily POACOIDEAE.. 
Tribe ORYZEAE. 
1. Spikelets unisexual, unlike in appearance.ZIZANIA. 
Spikelets consisting of perfect flowers.LEERSIA, 
Tribe PHALARIDEAE. 
X. Third and fourth glumes small and empty or rudimentary.... 
. PHALARIS. 
Third and fourth glumes enclosing staminate flowers.. 
. HIEROCHLOE. 
Tribe AGROSTIDEAE. 
1. Lemma indurated at maturity.2. 
Lemma membranous . 3. 
2. Spikelet awnless, no callus.MILIUM. 
Spikelets with a terminal awn, callus at the base.STIPA. 
3. Lemma awned from the tip or mucronate, closely infolding the 
grain. .4. 
Lemma awnless or dorsally awned, loosely embracing the grain..5. 
4. Rhachilla not prolonged behind the palea; lemma pointed or awned. 
. MUHLENBERGIA. 
Rhachilla prolonged into a bristle behind the palea; lemma long 
awned.BRACHYELYTRUM. 
5. Glumes conspicuously compressed, carinate; spikelets in dense 
spike-like panicles ...... 6 . 
Glumes not conspicuously compressed; spikelets in open or narrow 
panicles.7. 
