GR AMINE AE (GRASS FAMILY) 89 



29. Phleum. Lemma hyaline, awnless, glumes abruptly aristate ; panicle exserted, cylindiical. 



30. Alopecurus. Lemma hyaline, awned below the middle; palea none; glumes not aristate; 



panicle exserted, cylindrical. 



♦+ ++ Glumes not conspicuously compressed ; spikelets in open or narrow panicles. — Agi;o>'i1mae. 

 = Lemma 1 (rarely 3) -nerved, awnless ; pericarj) readily separating from the grain. 



31. Sporobolus. Lemma as long as or longer than the glumes ; culms wiry or rigid. 



= = Lemma 3-5-nerved, awued or awnless ; pericarp adherent to the grain. 

 a. Floret not stipitate ; jjalea 2-nerved ; stamens 3. 

 b. Khachilla not prolonged behind the palea. 



82. Agrostis. Glumes longer than the floret, awnless ; panicle usually open. 



33. Polypogon. Glumes longer than the floret, awned ; panicle spike-like. 



34. Galamovilfa. Glumes shorter than the floret, awnless. 



h b. Khachilla prolonged behind the palea, bristle-like. 



85. Calamagrostis. Perennial; panicle loose or contracted ; prolonged rhachilla and callus with 



long hairs ; lemma short-awned below the middle. 

 30. Ammophila. Perennial ; panicle dense and spike-like ; prolonged rhachilla and callus with 



short hairs ; lemma awnless. 



37. Apera. Annual ; panicle loose ; the prolonged rhachilla naked ; lemma loiig-awned below the 



bifid apex. 



a a. Floret stipitate ; palea 1-2-nerved ; stamen 1. 



38. Cinna. Spikelets in a loose panicle. 



Tribe VIL AV^NEAE. Spikelets 2-several-flowered, panicled ; rhachilla prolonged behind the 

 palea of uppermost floret except in Aira; glumes usually longer than the first floret ; 1 or 

 more of the florets awned on the back or from the teeth of the bifid apex (or usually awnless in 

 Sphenopholis and Koeleria) ; the callus and usually the rhachilla-joints hairy. 



* Rhachilla not prolonged behind the palea of uppermost floret; spikelets 2-flowered, both perfect. 



39. Aira. Florets approximate; glumes broad, boat-shaped. 



* * Ehachilla prolonged behind the palea of uppermost floret ; spikelets 2-several-flowered. 



-H Articulation below the glumes ; spikelets falling entire or the glumes and lowest floret together, 



++ Glumes much exceeding the two florets. 



40. Holcus. Lower floret stipitate, awnless, upper with a hook-like awn. 



++ -M- Glumes exceeded by uppei floret. 

 4L Sphenopholis. Glumes dissimilar, the second obovate; florets usually awnless. 

 +- -f- Articulation above the glumes. 

 ■H- Awns wanting or but a mucronate tip. 



42. Koeleria. Glumes unequal, exceeded by the upper floret. 



■H- ■»+ Awns present. 

 = Awns dorsal, not flattened. 

 a. Spikelets 2-several-flowered ; florets all perfect or the uppermost imperfe 

 b. Spikelets less than 1 cm. long ; grain free. 



43. Trisetum. Lemma keeled, bidentate, awn arising from above the middle. 



44. Deschampsia. Lemma convex, awn from the middle or below. 



b b. Spikelets more than 1 cm. long ; grain adherent to the palea. 



45. Avena. Florets approximate, exceeded by the striate glumes. 



a a. Spikelets 2-flowered ; lower floret staminate, upper perfect. 

 4(i. Arrhenatherum. Lower floret long-awne«i, upper usually awnless. 



=-= = Awns from between the teeth of the bidentate apex of the lemma, flattened, twisted, 

 47. Danthonia. Florets several, not closely approximate, glumes eoualing or exceeding the 

 uppermost. 



