192 



CYPERACEAE 



style long, its branches much shorter than the united lower part. 

 Spikelets in 1-4 dense globose heads. 



Achene truncate, tipped by a subulate tubercle, ciliate. 

 Achene obovoid, tipped by a conic tubercle, not ciliate. 

 Spikelets in panicled clusters : achene capped by a stout tubercle. 



Mature spikelets about I cm. long : tubercle slightly longer than the achene. 

 Mature spikelets much over 1 cm. long : tubercle several times longer than 

 the achene. 

 Style short, its branches as long as the united part or longer. 

 "Perianth-bristles none or very short. 

 Achene transversely wrinkled. 

 Achene smooth or reticulated. 



Achene reticulated, 0.. 5-0.7 mm. long : spikelets loosely corymbose. 

 Achene smooth, 1.5-2 mm. long : spikelets corymbose-capitate. 



Stem-leaves with blades 0.7 mm. wide or less : spikelets 3-4 mm. long. 

 Stem-leaves with blades 1.5-2.5 mm. wide : spikelets 4-6 mm. long. 

 Perianth-bristles present and usually well developed. 

 Bristles plumose : achene wrinkled. 



Spikelets solitaiy or 2-4 together. 6-S mm. long. 

 Spikelets numerous, clustered, 2. .5-4 mm. long. 



Perianth-bristles plumose nearly or quite to the top. 

 Stems slender, 1.5-3.5 dm. tall : spikelets small 

 Stems stout, 3-6 dm tall : spikelets large. 

 Perianth-bristles plumose below the middle or only near the base. 

 Bristles not plumose. 



Bristles retrorsely barbed. 



Scales pale green or white : perianth-bristles 9-24. 

 Scales brown : perianth-bristles 6. 



Spikelets few to numerous in rather loose, often panicled clusters. 

 Spikelets numerous, in 2— J dense globose heads, 

 Spikelets 5-6 mm. long : achene 2.5 mm. long. 

 Spikelets 3-3.5 mm. long : achene 1.5 mm. long. 

 Bristles upwardly barbed. 



Achene smooth or cancellate, not transversely wrinkled. 

 Achene smooth. 



Tubercle of the achene ciliate to serrulate. 

 Leaf-blades flat. 

 Leaf-blades channeled, involute, filiform or nearly so. 



Achene linear-oblong : perianth-bristles much overtopping 



the tubercle. 

 Achene obovoid : perianth-bristles not longer than the 

 achene and tubercle, or scarcely so. 

 Achene 1 mm. long or less, light Vjrown. 

 Achene 1..5-2 mm. long, dark brown. 

 Tubercle of the achene smooth or merely granular. 

 Perianth-bristles as long as the achene or longer. 

 Leaf-blades 0.,5-2 mm. wide. 



Perianth-bristles about as long as the achene. 

 Perianth-bristles much longer than the achene. 

 Leaf-blades 2-7 mm. wide. 

 Perianth-bristles much shorter than the achene, sometimes 

 very short. 

 Leaf-blades 0.5-3 mm. wide : spikelets 2-5 mm. long. 

 Leaf-blades narrowly linear: spikelets 2-3 mm. long. 

 Leaf-blades bristle-like, filiform : spikelets 4-5 mm. long. 

 Leaf-blades 4-10 mm. wide : spikelets 6-8 mm. long. 

 Achene cancellate. 



Leaf-blades broadly linear, blunt or merely acute : achene 1.5 



mm. long. 

 Leaf-blades narrowly linear, attenuate. 



Achenes 2.5 mm. long, equalling or shorter than the bristles. 

 Achenes 1.5 mm. long, much longer than the bristles. 

 Achene transversely wrinkled. 



Perianth-bristles shorter than the achene. 



Leaf-blades and stems fihform : spikelets flliform-pedicelled. 

 Leaf-blades not filiform, flat or involute: spikelets sessile or 

 short- pedicelled. 

 Leaf-blades involute. 



Achene flat, 1.5 mm. long, continuous with the tubercle. 

 Achene strongly biconvex, 2 mm. long, constricted under 

 the tubercle. 

 Leaf-blades flat. 



Achene biconvex, not constricted under the tubercle. 

 Achene 1mm. long : tubercle depressed, wider than high. 

 Achene 1.5 mm. long : tubercle conic, about as high as 

 wide. 

 Achene compressed, constricted under the tubercle. 

 Perianth-bristles as long as the achene or longer. 

 A. Spikelets ovoid to globular, 2-4 mm. long. 

 a. Achene not stipitate. 

 * Tubercle setose. 



t Spikelets 1-3-flowered. 



Perianth-bristles not longer than the achene and 



tubercle. 

 Perianth-bristles longer than the achene and tubercle. 

 Achene broadly or orbicular-obovoid. 

 Achene narrowly obovoid. 



1. R. Traci/i. 



2. R. solitdria. 



3. R. Indianolensis. 



4. R. corniculata. 



5. R. piimlla. 



6. R. divtrgem. 



7. R. Chafmanii. 



8. R. pallida. 



9. R. oligantha. 



10. 

 11. 



12. 



17. 



18. 



19. 



20. 



21. 

 22. 

 23'. 



24. 

 25. 

 26. 



28. 

 29. 



R. plumosa. 

 R. intermedia. 

 R. semiplumosa. 



R. alba. 



R. glomerata. 



R. axillaris. 



R. microcephala. 



R. fuscoides. 

 R. Curtissii. 



R. fiUfoHa. 



R. leptorhyncha. 



R. diatans. 

 R. gracilenia. 

 R. Baldwinii. 



R.fascicrdaris. 

 R. brachychaeta, 

 R. dodecandra. 



R. ciliata. 



R. Grayi. 

 R. Plankii. 



30. R. rariflora. 



31. 

 32. 



R. Torreyana. 

 R. Earlei. 



33. R. perplcxu. 



34. 

 35. 



R. cymosa. 

 R. coiiipressa. 



36. R. pahda. 



37. 

 38. 



R. raduca. 

 R. mixta. 



