296 TRIAN0RIA DIGYNIA. 



* * Flowers inferior. 



t Complete. 



17 XYRIS. Fl. in a roundish or oblong head. Cal. glumaceous, cartil- 

 aginous, 3-valved. Cor. 3-pctalled, equal. Stig. 3-cleft. Cans. 

 1 -celled, 3-valved. 



1 1 Incomplete. 



18. SISYRINCH1UM. Spath. 2-leaved. Cor. 6-petalled, flat, equal. 



Stam. cohering below. Stig. 3-cleft. Caps. 3-celled. 

 * * * Flowers glumaceous. 



19. SCIRPUS. Glum. 1-valved, 1-flowered, imbricated on all sides. 



Cor. 0. 



20. SCHQENUS. Glum, fascicled into a spike, paleaceous ; the infe- 

 rior ones empty. Cor. 0. Style deciduous. Seed 1, (mostly naked at 

 the base.) 



21. RHYNCHOSPORA. Glum, fascicled into a spike ; the inferior 

 ones empty. Cor. 0. Seed 1, crowned with the persistent style ; 

 base surrounded with bristles. 



22. MARISCUS. Fl. distinct, in a somewhat imbricated spike. CaZ. 

 2-valved, unequal, 3-flowered. Cor. 1-valved. Style 3-cleft. Seed 

 triquetrous. 



23. DULICHIUM. Spikes somewhat racemose, axillary; spikdets 

 linear-lanceolate, rather compressed. Glum, distichous, sheathing. 

 Cor. 0. Style very long, bifid ; base persistent. Seed with bristles at 

 the base. 



24. CYPERUS. Spikelets compressed, distinct. Glum, imbricated ih 

 two rows. Cor. 0. Style deciduous. Seed naked. 



25. ERIOPHORUM. Glum. 1-valved, imbricated on all sides into a 



spike. Cor. 0. Seed surrounded with long dense wool. 



26. SPARTINA. Fl. in unilateral spikes, imbricated in 2 rows. Cal. 

 2-valved, compressed, unequal. Cor. 2-valved, awnless, unequal. 

 Nect. collateral. 



27. ORYZOPSIS. Cal. 1-flowered, 2-valved ; valves membranaceous, 

 nearly equal, loose, obovate, awnless. Cor. 2-valved, coriaceous, cyl' 

 indrical-ovate, hairy at the base ; the inferior valve awned at tip 

 Nect. linear, elongated. 



DIGYNIA. 



A. Flowers all perfect. 



t Spikelets l-fiowered. 



* Cal.O. 



28. LEERSIA. Cal. 0. Cor. 2-valved, closed; valves compressed, 

 boat-shaped. Nect. obovate, entire, collateral. 



* * Cal. 2-valved. 

 a. Cor. without abortive rudiments at the base. 



} . Glumes and corolla of dissimilar texture ; the inferior valve involv- 

 ing the superior. 



