CYPERACEAE 
Leaf-blades 4-6 mm. wide: spikes loosely flowered. 
Leaf-blades 6-10 mm. wide: spikes dense. 
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. 
Perigynia many-nerved, dull: leaf-blades 4-10 mm. wide. 
Pistillate spikes cylindric: achenes not longer than thick. 
II. VESICARIAE. 
Scales acute, acuminate or smooth-awned, or the lower slightly roughened. 
Spikes few-several-flowered: perigynia little inflated, gradually beaked. 
Spikes many-flowered : perigynia much inflated, abruptly beaked. 
Scales tapering into rough awns. 
See oe 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 em. long: perigynia ascending. 
Pistillate spikes narrowly cylindric, 3-7 em. long: perigynia reflexed. 
IV. SQUARROSAE. 
Scales linear-subulate, longer than the perigynia. 
Scales lanceolate, 14 as long as the perigynia. 
Spikes 1-3, subglobose or oval, staminate below: achenes linear-oblong. 
Spikes a oblong-cylindric, usually staminate at both ends: achenes 
ovoid. 
V. PALUDOSAE. 
Leaves bright green, not glaucous: teeth of the perigynium-beak slender, 
conspicuous. ; 
Leaves pale green, glaucous: teeth of the perigynium-beak short. 
VI. SHORTIANAE. 
A single species in our range. 
VIT. ANOMALAE. 
Perigynía 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 e or spikes distinctly stalked. 
Leaves glabrous: native species. 
Leaf-blades flat, or their margins slightly revolute. 
Seales only 12 as long as the perigynia: coast species. 
Reales 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. 
A single species in our range. 
! i X. RIGIDAE. 
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. . 3 
Perigynia strongly several-nerved, about equalling the scales in length. 
Spikes erect. 
Spikes drooping, filiform-stalked. 
PAD XIV. VIRESCENTES. 
Perigynia densely pubescent. : 
Pistilate spikes oblong-cylindrie, 8-20 mm. long: perigynia oval or 
. ,,ovoid, few-nerved. pel 
Pistillate ee 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 
,, àchene not bent. 
Spikes 3-4 mm. thick: perigynia not imbricated, swollen: top of the 
achene bent or tipped with a bent style. 
4. C. intumescens. 
9. C. Asa-Grayi. 
6. C. Louisianica. 
7. C. lupulina. 
8. C. grandis. 
9. C. turgescens. 
10. C. bullata. 
11. C. lurida. 
12. C. Baileyi. 
13. C. hystricina. 
14. C. comosa. 
15. C. Frankii. 
16. C. squarrosa. 
17. C. typhinoides. 
18. C. trichocarpa. 
19. C. riparia. 
20. C. Shortiana. 
21. C. scabrata. 
22. C. Joorit. 
28. C. vestita. 
24. C. Walteriana. 
25. C. lanuginosa. 
26. C. filiformis. 
27. C. hirta. 
28. C. fusca. 
29. C. stricta. 
30. C. torta. 
31. C. prasina. 
32. C. littoralis. 
33. C. erinita. 
34. C. gynandra. 
35. C. macrokolea. 
36. C. verrucosa. 
37. C. virescens. 
88. C. costellata. 
39. C. triceps. 
40. C. Caroliniana. 
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