546 GRAMINE^. (grass FAlIILY.j 



» ♦ Olames distinct, concave or keeled. Paleae membranaceous. Grain free. Spikelets in 

 open or contracted panicles- 



5. SPOROBOLUS. Tlowers awnless. Seed loose in tlie globose or oboToid pericarp. 



6. VILFA. Flowers awnless. Seed adhering to the closely investing pericarp. 



7. AGROSTIS. Paleae shorter than the nearly equal glumes, the lower awned on the back, 



the upper sometimes wanting. 

 8- POLYPOGON. Paleae much shorter than the long-awned glumes, the lower one truncated 



and toothed. Stamens 3. Panicle spike-like. 

 9. CINNA. Paleae rather longer than the acute glumes, the lower one awned under the apex. 



Stamen 1. Panicle loose. 



10. MUHLENBERGIA Lower glume smaller than the upper one. Paleae bearded at the 



base, the lower one mucronate or awn pointed. Stamens .3. 



11. BRACIIYELVTRUM. Lower glume obsolete Lower palea locg-awned. A pedicel of a 



second flower at the back of the upper paleas. Stamens 2. 



12. CALAMAGROSTIS. Paleae surrounded with a tuft of long hairs, the lower awned on the 



back. 



• * » Paleae raised on a hairy stalk ; the lower one awned, indurated, and involute, closely 

 investing the grain. 



13. STIPA Lower palea with a single contorted awn jointed with its apex Panicle short. 



14. STREPTACIINE. Lower palea with a single straight or curved awn continuous with its 



apex. Panicle elongated. 



15. ARISTIDA. Lower palea triple-awned. Panicle elongated. 



Tribe III. CHLORIDEJE. — Spikelets 2 -several-flowered (in No. 16 one-flowered), in 

 1-sjded spikes. Rachis jointless. Upper flowers imperfect- Glumes and paleae 2. Spikes 

 racemed or digitate, rarely single. 



» Spikelets strictly 1-flowered. (See Paspalum.) 



16. SPARTINA. Spikelets flat, imbricated in alternate spikes. 



* * Spikelets 2-3-flowered, only the lowest flower perfect. 



17. GYMNOPOGON. Spikelets linear, scattered. Lower palea and rudiment awned. Spikes 



racemed. 



18. EUSTACHYS. Spikelets roundish, crowded. Lower palea mucronate. Spikes digitate. 



19. CYNODON. Lower palea awnless. Culms creeping. Spikes digitate. 



# * ♦ Spikelets 4 ■• 5-flowered, one of the middle ones only perfect. 



20. CTENIUM. Lower palea stout-awned on the back. Spike solitary. 



* * » « Spikelets mostly several-flowered, the lower flowers perfect. 



21. DACTYLOCTENIUM. Spikes digitate. Upper glume awned. Paleae pointed. 



22. ELEUSINE. Spikes digitate. Glumes and paleae awnless. 



23. LEPTOCULOA. Spikes racemed, long and slender. Glumes awnless. 



Tribe IV. PESTUCACE-iE. — Spikelets panicled, few -many -flowered; tbeupperand 

 (in No. 36 and 37) the lower flowers also imperfect. Glumes 2. Paleae 2, membranaceous 

 or rarely indurated, awnless, or the lower one with a straight awn at or near the apex- 

 Stamens 1-3 



• Grain smooth, free from the paleae. Lower flowers perfect. 

 t- Lower palea 3 - 5-toothed or awned. 



24. TRICUSPIS. Spikelets 6-7 flowered. Lower palea slightly 2-cleft, the 3 hairy nerves 



percurrent. 



25. TRIPL.\SIS. Spikelets 3-flowered, the lower palea deeply 2-cleft, and with a plumose 



awn between the teeth. 



