39. Trisetum. Spikelets 2–several-flowered. Flowering glume thin, compressed, carinate, 2-toothed, awned above by the excurrent mid nerve.
40. Avena. Spikelets 2–several-flowered. Flowering glume hard and firm, rounded on the back, 5–9 nerved, the mid-nerve long-excurrent at or below the 2-toothed apex.
41. Danthonia. As Avena, but the 3 middle nerves of the flowering glume running into a flattish twisted awn from between the teeth.
Tribe VIII. CHLORIDEÆ. Spikelets 2–several-flowered with one or more of the upper flowers imperfect (flower 1 and perfect in n. 45) arranged in 2 rows upon the rhachis of a 1-sided spike.
[*] Spikelets with one perfect flower.
42. Cynodon. Spikes 3–5, slender, digitate. Flower and the rudiment awnless.
43. Ctenium. Spike solitary, terminal. Flowers 4–6, the middle one perfect.
44. Gymnopogon. Spikes filiform, racemose. Spikelets remote, of a perfect flower and an awned rudiment.
45. Schedonnardus. Spikes 3–9, slender, scattered, distant. Spikelets small, 1-flowered awnless.
46. Bouteloua. Spikes scattered (rarely 1 and terminal), dense. Glume of perfect flower 3-toothed. Rudimentary flowers 1–3 awned.