35 6 CYPERACEAE. Vol. I. 



Perigynia closely appressed, or if somewhat spreading-ascending, the spikes whitish 

 or silvery green. 

 Spikes approximate, the head stiff ; lateral spikes rounded or little clavate at base. 

 Perigynia ovate, tapering into beak half length of body or more. 



Perigynia broader, abruptly contracted into beak about third length of body. 

 Scales long acuminate or aristate ; perigynia more than 2" long and nearly 



i'A" wide or more; achenes stipitate. 73. C.alata. 



Scales obtuse or acutish ; perigynia i^"-2" long (rarely slightly more) 

 and 1 54" or less broad; achenes nearly sessile. 74. C.albolutescens. 

 Spikes in a moniliform flexuous head ; lateral spikes long clavate. 75. C. silicea. 

 b. Scales very slightly shorter to slightly longer than perigynia and concealing them. 



Scales strongly dark-tinged, narrowly hyaline-margined ; head stiff, the spikes approximate, 



many-flowered. 76. C. leporina. 



Scales usually not dark-tinged, strongly hyaline margined ; if dark-tinged not as above. 

 Inflorescence stiff, the spikes closely approximate. 



Spikes elliptic, tapering at base; perigynia closely 'appressed; bracts scale-like. 



77. C. xerantica. 

 Spikes suborbicular, rounded at base ; perigynia loosely ascending ; lower 1-2 bracts 

 prominent, stiff. 78. C. adusta. 



Inflorescence not stiff, often flexuous and moniliform. 

 Perigynia nerveless on inner face or faintly nerved. 



Perigynia lance-ovate, 2j4"-3/4" l° n g, 1" wide or less; leaves about 1" wide. 



79. C. praticola. 

 Perigynia ovate, 2"-2 l / 2 " long, i"-ij£" wide; leaves ij£"-2 w wide. 



80. C. aenea. 

 Perigynia strongly nerved on inner face. 81. C.foenea. 



17. Phyllostachyae. 

 Scales (except lowest) not leaf-like, not enveloping perigynia, green with hyaline margins. 



Body of perigynia oblong; pistillate flowers usually 3-10. 82. C. Willdenovii. 



Body of perigynia globose; pistillate flowers usually 2-3. 83. C.Jamesii. 

 Scales leaf-like, half-enveloping perigynia, without conspicuous hyaline margins. 84. C. durifolia. 



18. Polytrichoideae. Represented by 1 species. 85. C.leptalea. 

 19. Pauciflorae. 



Racheola absent or rudimentary, not conspicuously exserted. 86. C. pauciflora. 



Racheola present, conspicuously exserted. 87. C. microglochin. 



20. Nitidae. Represented by 1 species. 88. C. supina. 



21. Rupestres. Represented by 1 species. 89. C.rupestris. 



22. Filifoliae. Represented by 1 species. 90. C. filifolia. 



23. Scirpinae. Represented by 1 species. 91. C. scirpoidea. 



24. Mitratae. Represented by 1 species. 92. C. caryophyllea. 



25. Montanae. 



1. None of the culms short and hidden among the bases of the leaves. 



Aphyllopodic and not stoloniferous ; lower sheaths but little fibrillose. 93. C. communis. 



Phyllopodic and often long-stoloniferous. 



Perigynia about equalling scales, i%" long or less. 



Staminate spike stout ; lower sheaths usually strongly fibrillose. 



Long stoloniferous; staminate spike 6"-i2" long. 94. C. pennsylvanica. 



Short stoloniferous ; staminate spike 2"-6" long. 95. C. varia. 



Staminate spike not over y 2 " thick; sheaths little fibrillose. 96. C.novae-angliae. 



Perigynia twice length of scales, iJ4"-2" long. 97. C. albicans. 



2. Many of the culms short and hidden among the bases of the leaves. 

 Lower bract exceeding the culm, leaf-like. 



Staminate spike i"-3" long; perigynia 1 yi" long, or less. 98. C.deflexa. 



Staminate spike 3"-6" long ; perigynia 2" long, or more. 99. C. Rossii. 



Lower bract exceeded by the culm, scale-like. 



Pistillate and staminate spikes contiguous; culms aphyllopodic. 100. C.nigromarginata. 



Lower pistillate spikes widely separate ; culms phyllopodic. 



Perigynia 2" long or less, puberulent ; leaves slender, light green, ascending, iyi" wide 



or less. 101. C. umbellata. 



Perigynia longer, glabrous except the long beak ; leaves stiff, deep green, spreading, wider. 



102. C. tonsa. 



26. Triquetrae. Represented by 1 species. 103. C. hirtifolia. 



27. Pictae. Represented by 1 species. 104. C.picia. 



28. Pedunculatae. Represented by 1 species. 105. C. pedunculated. 



29. DlGITATAE. 



Staminate spike i 1 A"-3" long; scales obtuse, one-half length of perigynia. 106. C. concinna. 



Staminate spike 6"-io" long; scales acute to acuminate, exceeding perigynia. 107. C. Richardsonii. 



30. Albae. Represented by 1 species. 108. C.ebumea. 



31. Bicolores. 



Mature perigynia whitish, ellipsoid, not fleshy or translucent. 109. C.Hassei. 



Mature perigynia orange or brownish, broader, fleshy, translucent. no. C.aurea. 



32. Paniceae. 



Perigynia beak none or very short, often bent. 



Leaves 1" wide or less, involute or folded; leaves and perigynia very glaucous; bract sheaths 



short ; spikes approximate. I ' ',• C. hvida. 



Leaves i"-3" wide, flat ; leaves green or bluish-green ; bract sheaths long ; spikes distant. 



Perigynia turgid ; peduncle of staminate spike smooth ; leaves bluish-green. 112. C.pamcea. 

 Perigynia not turgid ; peduncle of staminate spike rough ; leaves green. 



