POACEAE. 



19 



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 S. Festuceae. 



30. ECHINOCHLOA, 20. 



34. MUHLENBERGIA, 22. 



Tribe 1. PANICEAE. 



Spikelets in clustered racemes or spikes. 

 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. 

 Fruiting lemma firm and indurated. 

 Awns 3-branched. 

 Awns simple, twisted. 

 Lemma awnless or short-awned and loosely en- 

 veloping the grain. 

 Inflorescence a dense spike-like raceme or 

 panicle. 

 Lemma awnless. 

 Lemma awned. 

 Glumes awnless. 

 Glumes awned. 

 Inflorescence a loose panicle. 

 Palea 1-nerved, stamen 1. 

 Palea 2-nerved; stamens 3. 



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



utricle. 

 Lemma 3-5-nerved; fruit a grain. 



Callus with a tuft of long hairs at the 



base. 

 Callus naked. 



35. 

 36. 



Aristida, 22. 

 Stipa, 22. 



37. Phleum, 23. 



38. 

 39. 



40. 



41. 



42. 

 43. 



Alopecurus, 24. 

 polypogon, 24. 



Cinna, 24. 

 Sporobolus, 25. 



Calamagrostis, 25. 

 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. 

 Perfect flowers two or more. 



Awn of lemma from between the 2 terminal 



teeth. 

 Awn of lemma dorsal or none. 



Spikelets large, more than IS mm. long. 

 Spikelets small, less than 15 mm. long. 

 Lemma erose-truncate. 

 Lemma 2-toothed. 



45. Arrhenatherum, 27. 



46. Merathrepta, 28. 



47. AvENA, 28. 



48. 

 49. 



Deschampsia, 28. 

 Trisetum, 29. 



