POACEAE. 17 



Flowering glumes broad ; awn deciduous. 



Flowering glumes glabrous, or pubescent with short appressed hairs. 



i8. Oryzopsis. 

 Flowering glumes pubescent with long, silky hairs much exceeding 

 the glume. ig. Eriocoma. 



Flowering glumes narrow; glabrous or with short, appressed hairs; the 

 awn persistent. 20. Muhlenbergia. 



Spikelets in pairs, one perfect and the other staminate or sterile, in a spike- 

 like panicle. 21. Lycurus. 

 Flowering glumes usually hyaline or membranaceous at maturity ; at least more 

 delicate than the empty ones ; grains loosely enclosed. 

 Stigma, sub-plumose (i. e., with short hairs all around), projecting from the 

 apex of the nearly closed glumes. 

 Inflorescence spike-like. 



Rachilla of the spikelets articulated above the empty glumes, which are 



therefore persistent. 22. Phleum. 



Rachilla of the spikelets articulated below the empty glumes, hence the 

 spikelets deciduous entire. 23. Alopecurus. 



Inflorescence an open small panicle ; dwarf arctic-alpine plant. 



24. Phippsia. 

 Stigma plumose, projecting from the sides of the spikelets ; inflorescence an 

 open or spike-like panicle. 

 Grain not permanently enclosed in the flowering scale and palet ; pericarp 

 opening readily at maturity. 

 Flowering glumes long-hairy on the veins. 23. Blepharineueon. 



Flowering glumes not long-hairy on the veins. 26. Sporobulus. 



Grain permanently enclosed in the flowering glume and the palet; pericarp 

 adherent. , 



Spikelets readily falling off entire when mature. 27. Polypogon. 

 Spikelets with the empty scales at least persistent. 



Palet i-nerved and i-keeled; stamen i. 28. Cinna. 



Palet 2-nerved and 2-keeled or sometimes wanting; stamen 3. 

 Flowering glumes naked at the base. 29. Agrostis. 



Flowering glumes with long hairs at the base. 



Flowering glume and palet thin-membranous. 30. Calamagrostis. 

 Flowering glume and palet chartaceous. 31. Calamovilfa. 



Tribe 7. AVENEAE. 



Awn of the flowering glumes inserted dorsally below the teeth. 

 Grain free, unfurrowed ; spikelets less than i cm. long. 



Flowering glumes erose-toothed or shortly 2-lobed at the apex. 



32. Deschampsia. 

 Flowering glumes 2-cleft or deeply 2-toothed at the apex ; teeth awn-pointed. 

 Awn twisted and bent. 33. Trisetum. 



Awn if present not twisted, straight. 34. Graphephorum. 



Grain furrowed, adherent to the glumes ; spikelets exceeding i cm. in length. 

 Ovary not crowned by a villous appendage. 35. Avena. 



Ovary crowned by a villous appendage (awned species of) 



65. Bromus. 

 Awn of the flowering glumes inserted between the teeth. 36. Danthonia. 



Tribe 8. CHLORIDEAE. 



Spikelets with perfect flowers. 



Spikelets with i (rarely 2) perfect flowers. 



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

 Rhachis produced above the upper spikelet ; spikelets narrow. 



37. Spartina. 

 Rhachis not produced beyond the upper spikelet ; spikelets globose. 



38. Beckmannia. 



