POACEAE. 1 9 



spike-like panicle or raceme. 

 Lemmas shorter than the glumes, usually 



with a bent awn rising from the back. Tribe 4. Aveneae. 



Lemmas longer than the glumes, awnless 



or with a straight apical awn. Tribe 5. Festuceae. 



Tribe 1. PANICEAE. 



Spikelets in clustered racemes or spikes. 30. Echinochloa, 20. 



Spikelets not in clusters. 



Inflorescence a dense spike-like panicle; pedicels 



bristly. 31. Chaetochloa, 20. 



Inflorescence a loose panicle; pedicels not bristly. 32. Panicum, 21. 



Tribe 2. PHALARIDEAE. 

 First and second lemmas small, empty and not awned. 33. Phalaris, 21. 



Tribe 3. AGROSTIDEAE. 



Lemma with a long terminal awn and closely en- 

 veloping the grain. 

 Fruiting lemma thin and membranaceous. 34. Muhlenbergia, 22. 



Fruiting lemma firm and indurated. 



Awns 3-branched. 35. Aristida, 22. 



Awns simple, twisted. 36. Stipa, 22. 



Lemma awnless or short-awned and loosely en- 

 veloping the grain. 

 Inflorescence a dense spike-like raceme or 

 panicle. 

 Lemma awnless. 37. Phleum, 23. 



Lemma awned. 



Glumes awnless. 38. Alopecurus, 24. 



Glumes awned. 39. Polypogon, 24. 



Inflorescence a loose panicle. 



Palea 1-nerved, stamen 1. 40. Cinna, 24. 



Palea 2-nerved; stamens 3. 



Lemma 1-nerved, rarely 3-nerved; fruit a 



utricle. 41. Sporobolus, 25. 



Lemma 3-5-nerved; fruit a grain. 



Callus with a tuft of long hairs at the 



base. 42. Calamagrostis, 25. 



Callus naked. 43. Agrostis, 26. 



Tribe 4. AVENEAE. 



Perfect flower only one, the other staminate. 

 Lower flower perfect, awnless; upper staminate, 



awned. 44. Holcus, 27. 



Lower flower staminate, long awned; upper 



perfect, awnless. 45. Arrhenatherum, 27. 



Perfect flowers two or more. 



Awn of lemma from between the 2 terminal 



teeth. 46. Merathrepta, 28. 



Awn of lemma dorsal or none. 



Spikelets large, more than 15 mm. long. 47. A vena, 28. 

 Spikelets small, less than 15 mm. long. 



Lemma erose-truncate. 48. Deschampsia, 28. 



Lemma 2-toothed. 49. Trisetum, 29. 



