CYPERACEAE 



203 



Leaf-blades 4-6 mm. wide : spikes loosely flowered. 4. C. intumescens. 



Leaf-blades 6-10 mm. wide : spikes dense. 5. C. Asa-Grayi. 

 B. Pistillate spikes oblong or cylindric, densely many-flowered. 

 Pistillate spikes oblong : achenes longer than thick. 



Perigynia strongly several -nerved, shining : leaf-blades 2-4 mm. wide. 6. C. Louisianica. 



Perigynia many-nerved, dull : leaf-blades 4-10 mm. wide. 7. C. lupulina. 



Pistillate spikes cylindric : achenes not longer than thick. 8. C. grandis. 



II. VESICARIAE. 



Scales acute, acuminate or smooth-awned, or the lower slightly roughened. 



Spikes few-several-flowered : perigynia little inflated, gradually beaked. 9. C. turgescens. 

 Spikes many-flowered : perigynia much inflated, abruptly beaked. 10. C. bullata. 



Scales tapering into rough awns. 



Spikes stout-cylindric, about 12 mm. thick : perigynium tapering into a 



beak. 



Spikes narrowly cylindric, 6-8 mm. thick : perigynium abruptly nar- 

 rowed into a beak. 



III. PSEUDOCYPERINAE. 



Pistillate spikes oblong-cylindric, 1-3 cm. long : perigynia ascending. 13. C. hystricina. 



Pistillate spikes narrowly cylindric, 3-7 cm. long : perigynia reflexed. 14. C. cbmosa. 



IV. SQUARROSAE. 



Scales linear-subulate, longer than the perigynia. 15. C. Frankii. 



Scales lanceolate, % as long as the perigynia. 



Spikes 1-3, subglobose or oval, staminate below: achenes linear-oblong. 16. C. squarrosa. 



Spikes 2-6, oblong-cylindric, usually staminate at both ends: achenes 



ovoid. 17. C. typhinoides. 



V. PALUDOSAE. 



Leaves bright green, not glaucous : teeth of the perigynium-beak slender, 



conspicuous. 18. C. trichocarpa. 



Leaves pale green, glaucous : teeth of the perigynium-beak short. 19. C. riparia. 



VI. SHORTIANAE. 

 A single species in our range. 



VII. ANOMALAE. 



Perigynia ovoid, longer than the scales. 

 Perigynia short-obovate, about equalling the serrate-awned scales. 



VIII. HIRTAE. 



Staminate spike or spikes sessile or nearly so. 

 Staminate spike or spikes distinctly stalked. 

 Leaves glabrous : native species. 



Leaf-blades flat, or their margins slightly revolute. 

 Scales only % as long as the perigynia : coast species. 

 Scales as long as the perigynia or only slightly shorter : Alleghenian 



species. 



Leaf-blades strongly revolute, 2 mm. wide or narrower. 

 Leaves, at least their sheaths, pubescent : naturalized species. 



IX. ATRATAE. 

 X. RIGIDAE. 



A single species in our range. 



A single species in our range. 



XI. PRASINAE. 



Perigynia twisted toward the top : scales purple-brown. 

 Perigynia straight : scales green. 



XII. PENDULINAE. 

 A single species in our range. 



XIII. CRYPTOCARPAE. 



Perigynia nerveless or faintly nerved, much shorter than the scales. 



Perigynia obovoid, obtuse. 



Perigynia oblong or elliptic, acute. 

 Perigynia strongly several-nerved, about equalling the scales in length. 



Spikes drooping, filiform-stalked. 



XIV. VIRESCENTES. 



Perigynia densely pubescent. 



Pistillate spikes oblong-cylindric, 8-5 



ovoid, few- nerved. 

 Pistillate spikes narrowly cylindric, 12-36 mm. long : perigynia oblong, 



strongly many-nerved. 

 Perigynia glabrous or nearly so, at least when mature. 



Spikes 5-7 mm. thick : perigynia imbricated, flattened : top of the 



achene not bent. 

 Spikes 3-4 mm. thick : perigynia not imbricated, swollen : top of the 



achene bent or tipped with a bent style. 



-20 mm. long: perigynia oval or 



20. C. Shortiana. 



21. C. scabrata. 



22. C. Joorii. 



23. C. vestita. 



24. C. Walteriana. 



25. C. lanuginosa. 



26. C. niiformis. 



27. C.'hirta. 



28. C.fusca. 



29. C. stricta. 



30. C.torta. 



31. C. prasina. 



32. C. littoralis. 



33. C. crinita. 



34. C. gynandra. 



35. C. macrokolea. 



36. C. verrucosa. 



37. C. virescehs. 



38. C. costellata. 



39. C. triceps. 



40. C. Caroliniana. 



