414 GRAMINE^. 



15. SxrpA. Glumes 2, membranaceous, awnless, nearly equal. Palese coriaceous, involute : awn twisted. Scales shorter 



than the stipitate ovary. 



16. Akistid.*.. Glumes unequal, mostly awnless. Palece involute ; the lower with a 3-parted awn at the tip. 



Tribe 5. AGROSTIDEjE. Spikelets one-flowered, rarely with another rudimentary flower. Glumes and paleae 

 2, membranaceo-herbaceous ; the lower palea often awned. 



17. MuHLENBEBGiA. Glumes unequal. Pales lanceolate, mostly hairy at the base ; the lower one mucronate or awned 



at the tip. — Panicle more or less contracted. 



18. ViLFA. Glumes unequal, not keeled. Palea not bearded ; the lower one awnless. 



19. Aghostis. Glumes unequal. Palea> mostly shorter than the glumes : lower one commonly awned on the back ; 



the upper one often minute. — Panicle diffuse. 



20. Brachyelytrum. Glumes very minute. Lower palea with a long terminal awn ; upper with a clavate rudimen- 



tary flower at the base. — Panicle racemose. 



Tribe 6. ARUNDINACE^. Spikelets one-flowered, with a rudimentary flower; or many-flowered : the flowers 

 usually with long hairs at the base. Glumes and palea! 2, membranaceo-herbaceous. — Inflorescence 

 paniculate. 



21. Calamagrostis. Spikelets one-flowered, and sometimes furnished with a pencil-form rudiment. Palea; surrounded 



with hairs at the base ; the lower one usually with a short awn at the apex or on the back. 



22. Ammophila. Palea; shorter than the carinate glumes, surrounded with hairs at the base, awnless. Scales elongated. 



23. Phragmites. Spikelets 3 - 6-flowered : flowers perfect, on villous pedicels, except the lowest, which is sessile, 



Etaminate, and naked at the base. 



Tribe 7. CHLORIDEjE. Spikes unilateral : spikelets one-flowered, or many-flowered with the upper flowers 

 imperfect. Glumes and palco; 2, herbaceo-membranaceous. 



24. Eleusine. Spikes digitate or fasciculate. Spikelets sessile, 2 - 6-flowered : flowers awnless. Glumes carinate. 



Seed transversely rugose. 



25. Sp.vrtina. Spikes disposed in a raceme, or remote and secund. Spikelets unilateral, closely imbricated in 2 rows. 



Glumes and palea; carinate, compressed, awnless. Styles mostly united below. 



26. BouTELOuA. Spikes short, disposed in a unilateral raceme, Spikelets 2 - 3-flowered. Glumes carinate ; the upper 



one much larger. Lower palea 3-toothed, or with 3 bristles at the summit. 



Tribe 8. AVENACE.S. Spikelets 2 - many-flowered ; the terminal flower usually imperfect. Glumes and paleiE 

 2, herbaceo-membranaceous ; the lower palea usually with a twisted awn on the back. 



27. Aira. Spikelets 2 - 3-flowered. Lower palea 2 - 4-toothed, awned on the back. 



28. Trisetum. Spikelets 2 - 4-flowered. Lower palea bicuspidate, with a twisted awn on the back below the cusps. 



Caryopsis not sulcate. 



29. AvENA. Spikelets several-flowered ; the flowers remote. Lower palea awned on the back. Caryopsis longitudinally 



sulcate on the inside. 



30. Arrhenatherum. Spikelets 2-flowercd. Lower flower staminate, with the lower palea awned on the back. 



Upper flower perfect ; the lower paica awnless, or with a short awn a little below the tip. 



31. Danthonia. Spikelets 2 - 5-flowcrcd. Glumes longer than the flowers (which are bearded at the base), cuspidate. 



Lower palea 2-toothed, with a twisted awn between the teeth. 



32. Uralepis. Spikelets 3 - 4-flowercd, somewhat terete. Glumes short. PaleiE unequal, villous on the margins : lower 



one tricuspidate, the central cusp produced into a short awn ; the upper bicarinate and incurved. 



Tribe 9. FESTUCACEjE. Spikelets many-flowered (rarely few-flowered). Glumes and palese 2, membranaceo- 

 herbaceous, rarely coriaceous : lower palea often with a sliort bristle. Inflorescence paniculate, some- 

 times contracted and .spike-like. 



33. PoA. Spikelets ovate, oblong or linear, compressed, 3 - many-flowered. Glumes shorter than the flowers. Paleae 



awnless, usually membranaceous, often with a web-like pubescence at the base. 



34. Glvceria. Spikelets terete, elongated, many-flowered. Paleat awnless ; upper one somewhat conduplicate. Scales 



collateral, connate. Stigmas decompound. 



35. Dactylis. Spikelets aggregated into a unilateral head, many-flowered. Glumes and paletc carinate, mucronate. 



