GRASSES OF OHIO 



((D). Panicle open: lemma usually awned. 



a. Flowers not stalked ; stamens 3 ; palet 2-nerved. 



(a). Lemma entire; rachilla not prolonged, or if so with 



a tuft of long hairs. 



((a)). Callus below the flowering glumes and the 



prolonged rachilla with a tuft of long 



hairs. Calamagrostis. (36) 



((b)). Callus naked or with short hairs: rachilla 



not prolonged. Agrostis. (37) 



(b). Lemma long-awed, with a bifid apex: rachilla pro- 

 longed into a short bristle. Apcra. (38) 



b. Flowers plainly stalked : stamen 1, palet usually 1 -nerved. 



Cinna. (39) 



((2)). Panicle narrow and contracted; lemma awnless. 



Ammophila. (40) 



2. Empty glumes conspicuously compressed-carinate ; spikelets in dense 

 spike-like panicles. 



(1). Empty glumes awnless. 



((D). Lemma awned below the middle; panicle exserted, cylindri- 

 cal. Alopecurus. (41) 

 ((2)). Lemma awnless; panicle partly included, ovoid. 



Heleochloa. (42) 



(2). Empty glumes awned; lemma awnless. Phleutn. (43) 



B. Lemma with a terminal awn or awn-pointed ; flowering glumes closely en- 

 closing the grain. 



1. Rachilla not prolonged behind the palet; empty glumes usually evident. 



Muhlenbergia. (44) 



2. Rachilla extending beyond the base of the palet into a bristle; empty 



glumes minute. Brachyelytrum. (45) 



IT. Flowering glumes indurated at maturity, firmer than the empty glumes. 



A. Lemmas awnless, their margins inrolled ; spikelets without a basal callus. 



Milium. (46) 



B. Lemmas awned. their margins flat ; spikelets with a basal callus. 



1. Awn simple. 



(1). Lemma broad, its awn straight and deciduous. Orycopsis (47) 

 (2). Lemma narrow, its awn twisted and persistent. Stipa. (48) 



2. Awn 3-branched; callus acute. Aristida. (49) 



Phalarideae. 



1. Empty glumes equal or nearly so. 



a. Third and fourth glumes (lemmas) subtending staminate flowers. 



Savastana. (50) 



b. Third and fourth glumes small and empty, or vestigial. Phalaris. (51) 



2. Empty glumes very unequal: third and fourth glumes dorsally awned. 



Ant ho. va nt hum. (52) 



