GRASS FAMILY 31 



stigma plumose, projecting from the sides of the spikelets; inflorescence an open or 

 spike-like panicle. 

 Grain not permanently enclosed in the lemma and palet; pericarp opening readily 

 at maturity. 

 Flowering glumes long-hairy on the veins. 26. Bleph.\ron'EURON. 



Flowering glumes not long-hairy on the veins. 27. Sporobolus. 



Grain permanently enclosed in the lemma and the palet; pericarp adherent. 

 Spikelets readily falling off when mature. 28. POLYPOGON. 



Spikelets with the emj)ty scales at least persistent. 



Palet l-nerved and 1-keeled; stamen 1. 29. Crx\.\. 



Palet 2-nerved and 2-keeled or sometimes wanting: stamens 3. 

 Lemma naked at the base. 30. Agrostis. 



Lemma with long hairs at the base. 



Flowering glume and palet tliin-membranous. 3 1 . C.\l.\m.\grostis. 

 Flowering glume and palet chartaceous. 32. C.\l.\movilfa. 



Tribe 7. AVENEAE. 

 Awn of the lemma inserted dorsally below the teeth. 

 Flowers all perfect or the upper staminate. 



Gram free, unfurrowed; spikelets less than 1 cm. long. 



Lemma eroso-toothed or shortly 2-lobed at the apex. 33. Desch.\mpsia. 

 Lemma 2-cleft or deeply 2-toothed at the ape.x; teeth awn-pointed. 

 Awn twisted and bent. 34. Trisettjm. 



Awn if present not twisted, straight. 35. Graphephorum. 



Grain furrowed, adherent to the glumes; spikelets e.vceeding 1 cm. In length. 

 Ovary not crowned by a villous appendage. 36 AVENA. 



Ovary crowned by a \lllous appendage (awned species of) 



70. Bromus. 

 Upper flowers perfect, the lower staminate. 37. Arrhenatherum. 



Awn of the lemma Inserted between the teeth. 38. D.-vnthonia. 



Tribe 8. CHLORIDEAE. 

 Plants with perfect flowers. 



Spikelets with 1 (rarely 2) perfect flowers. 



Spikelets deciduous as a whole; rachis articulated below the empty glumes. 

 Rachis produced above the upper spikelet; spikelets narrow. 



39. Spartina. 

 Rachis not produced above the upper spikelet; spikelets globose. 



40. Beckmannia. 

 Spikelets with at least the empty glumes persistent. 



Glumes above the perfect flower none; spikes digitate, very slender. 



41. SCHEDONNARDUS. 



Glumes above the perfect flower 1-several; spikes scattered. 



Spikes closely appro.\lmate, subverticUlate. 42. Chix)RIS. 



Spikes scattered. 43. Bouteloua. 



Spikelets with 2-3 perfect flowers; spikelets alternate. 44. Leptochloa. 



Plants dioecious; spikelets of the two sexes very unlike. 45. Bulbilis. 



Tribe 9. FESTUCEAE. 

 Lemmas, at least of the pistillate spikelets, 3-lobed and 3-awned; plant dioecious. 



46. SCLEROPOGON. 



Lemmas entire or at most 3-lobed. 



Hairs on the rachilla or the lemma very long and enclosing the latter. 



47. Phr.\gmites. 

 Hairs, if any, on the rachilla and the lemma shorter than the latter. 



Stigmas barbeUate on elongated styles; spikelets In threes In the axils of spinescent 



leaves. 48. MuiSfROA. 



Stigmas plumose, sessile or on short styles. 

 Lemma 1-3-nerved. 



Lateral nerves of the lemmas hairy. 

 Lemma deeply 3-lobed. 



Internodes of the rachilla long, often half as long as the lemma; 



plants without stolons. 50. Triplasis. 



Internodes of the rachilla short, many times shorter than the lemmas. 

 Fertile flower one, \iith 2 empty lemmas below and one above. 



49. Blepharid.ichne. 

 Fertile flowers 3 or more, with no empty lemmas below. 



51. Dasyochloa. 

 Lemma entire or slightly 2-lobed; Intemodes of the rachilla short. 

 Inflorescence a short congested raceme; leaf-blades with thick car- 

 tilaginous margins. 52. Erioneuron. 

 Inflorescence a panicle; leaf-blades not with cartilaginous margins. 

 Panicle simple or compound, the spikelets on pedicels of vary- 

 ing length. 52. Tridens. 

 Panicle composed of long branches, along wliich the appressed 

 spikelets are arranged on short pedicels. 



54. DlPL.\CHNE. 



Lateral nerves of the lemmas glabrous. 



Callus of the lemma copiously pubescent with long hairs; panicle open. 



55. Redfieldia. 



