32 CYPERACEAE. 



Achene not stipitate. 



Tubercle setose. 8. R. caduca. 



Tubercle not setose. 9. R. viiliacea. 



Achene stipitate. 10. R. stipitata. 



1. E. Tracyi Britton. Stems 5-12 dm. tall: leaf -blades channeled, 4-8 mm. 

 wide, straight, erect or ascending: heads 1-6, globose 1-2 cm. in diameter: 

 spikelets lanceolate, 5-6 mm. long, acuminate, pale: scales often 9. the fourth 

 one fertile: perianth-bristles 6, very slender: achene-body flat, obovoid or 

 cuneate-obovoid, 2.5-3 mm. long, minutely wrinkled, ciliate, exceeded by the 

 bristles; tubercle subulate, fully twice as long as the achene-body. — Ever- 

 glades. — {Bah., Cuia.) 



2. R. comiculata (Lam.) A. Gray. Stems smooth, 1-2 m. tall: leaf -blades 

 flat, 6-16 mm. wide, rough-margined: umbels sometimes 2-5 dm. broad: 

 spikelets spindle-shaped, much over 1 cm. long when mature, clustered at the 

 ends of the rays and raylets : scales lanceolate, thin, acute, light-brown : 

 perianth-bristles about 6, rigid, upwardly scabrous: 1-2.5 cm. long, much 

 exserted beyond the scales when mature: achene-body obovoid, flat, 4-6 mm. 

 long, dark-brown, smooth. — Everglades. 



3. R. divergens M. A. Curtis. Stems densely tufted, filiform or wiry, 1-4 dm. 

 tall: leaf -blades very slender: spikelets elliptic to ovoid-elliptic, 3-3.5 mm. 

 long, acute, in loose or rarely somewhat contracted corymbs: perianth-bristles 

 wanting: achene-body plump-lenticular, orbicular-obovoid, pale, 0.5-0.8 mm. 

 long, reticulate, pinched at the base; tubercle depressed, sessile. — Everglades. 

 — F. K. {Bah., Cuba.) 



4. R. ciliata (Michx.) Yahl. Stems not densely tufted, 3-8 dm. tall: leaf- 

 blades broadly linear, 5-8 mm. wide, ciliate, glaucous, blunt or merely acute: 

 spikelets narrowly ovoid or lanceolate, 5-6 mm. long, usually aggregated into 

 a solitary terminal capitate cluster: achene-body lenticular, cancellate, oval 

 or orbicular-oval, 1.5 mm. long; tubercle rather depressed, conic, exceeding the 

 bristles.-^Pinelands. 



5. R. Grasri Kunth. Stems often solitary, 3-7 dm. tall: leaf -blades mostly 2-3 

 mm. wide, attenuate: spikelets ovoid, 5-6 mm. long, chestnut-colored, aggre- 

 gated into usually 2-4 capitate clusters: achene-body lenticular, plump, cancel- 

 late, obovoid, or broadly oblong, 2-5 mm. long, dark-brown; tubercle de- 

 pressed-conic, overtopped by the bristles. — Pinelands. 



6. R. perplexa Britton. Stems 5-11 dm. tall, often tufted: leaf-blades flat, 

 1-2.5 mm. wide, usually much elongate: spikelets ovoid or orbicular-ovoid, 

 about 2 mm. long, in a terminal and 1 or several axillary lax or rarely slightly 

 congested corymbs on very slender peduncles: scales brown, blunt or merely 

 acute: achene-body biconvex, not constricted under the tubercle, about 1 mm. 

 long; tubercle depressed, wider than high, exceeding the bristles. — Pinelands. 

 — {Bah.) 



7. R. cymosa (Michx.) Ell. Stems tufted, 3-8 dm. tall: leaf -blades flat, 3-4 

 mm. wide or the basal ones broader: spikelets ovoid-oblong, acute, 3 mm. 

 long, sessile or nearly so, capitate in 2 's-7 's on the ultimate branches of the 

 axillary and terminal clusters: scales dark-brown, broadly ovate: achene-body 

 broadly obovoid or oblong-obovoid, lenticular, 1.5 mm. long, transversely 

 wrinkled; tubercle conic, about as high as wide, exceeding the bristles. — 

 Pinelands. — {Cuba, Ant.) 



8. R. caduca Ell. Stems often loosely tufted, 8-15 dm. tall: leaf-blades 4-10 

 mm. wide: spikelets ovoid, about 4 mm. long, numerous in 4-6 compound 

 corymbs: achene-body lenticular, orbicular-obovoid, about 1.5 mm. long, finely 

 transversely wrinkled: tubercle setose, conic, exceeded by the bristles. — Ever- 

 glades and coastal sand-dunes. 



