506 CTPERACEiE. (SEDGE FAMILT.) 



high ; leaves and 3-leaved involucre narrowly linear. (C. fasciculatus, Ell. ?) — 

 Low grounds, Florida, and nortliward. July and Aug. 



2. C. rivularis, Kunth. Umbel of 3 - 4 rays, one or two of them longer 

 than the spikelets ; spikelets 3-6 in a cluster, oblong-linear, acute, many-flow- 

 ered ; scales pale straw-color, ovate, obtuse, appressed ; rachis margined ; sta- 

 mens 2 ; nut round-obovate, transversely roughened, black and shining ; culms 

 6'- 12' high, slender; leaves and 3-leaved involucre linear. — Marshy banks of 

 streams, Georgia, Florida, and westward. Aug. 



3. C. diandrus, Torr. Umbel of 2 - 5 short and unequal rays, the longer 

 ones longer than the spikelets ; spikelets lanceolate-oblong, acute, brownish or 

 dark brown, spreading ; scales ovate, obtuse, appressed, green on the keel ; 

 rachis margined; stamens 2; nut oblong-obovate, roughish, dull gray. — Wet 

 places, North Carolina, and northward. Aug. — Culms 4'- 10' high. Invo- 

 lucre 3-leaved. This and the preceding are probably only diandrous forms of 



No. 1. 



* * Spikelets scattered on the common rachis {spiked). 



4. C Nuttallii, Torr. Umbel sessile or of 3 - 6 rays, 1' -2' long; spike- 

 lets numerous on the rays, spreading, linear-lanceolate, acute, light or yellowish 

 brown, 12-20-flowered, the lower ones commonly compound; scales rigid, ob- 

 long-ovate, acute or mucronate, appressed ; stamens 2 ; nut oblong-obovate, 

 very obtuse, grayish and minutely pitted; culms clustered, 3-angled, 4' -15' 

 high ; leaves and involucre narrowly linear. (0. flavescens, Ell. 0. holosericeus. 

 Link.?) — Salt or brackish soil, Florida, and northward. July -Sept. — Plant 

 commonly yellowish and glossy throughout. Spikelets rarely crowded in a 

 terminal head. 



5. C. flavicomus, Michx. Umbel compound, many-rayed ; spikelets very 

 numerous, crowded, linear, acute, 12 -30-flowered ; scales loosely imbricated, yel- 

 lowish, round-obovate, emarginate, with broad and scarious margins, at length 

 spreading ; rachis broadly margined ; stamens 3 ; nut obovate, black, smooth 

 and shining, barely shorter than the scale; culms thick, obtuse-angled, l°-3° 

 high; leaves broadly linear, glaucous beneath, as long as the culm. — Low 

 grounds and ditches, Georgia and South Carolina. May -Sept. — Involucre 

 3 - 5-leaved. Spikelets 6" - 9" long. 



6. ' C. microdontUS, Torr. Umbel of 4 - 8 rays, simple or somewhat 

 compound ; spikelets numerous, crowded, linear, acute, 1 5 - 2.5-flowered, pale 

 brown; scales thin, ovate, acute, closely imbricated; rachis slightly margined ; 

 stamens 2 ; nut linear-oblong or somewhat club-shaped, short-pointed, grayish 

 and minutely pitted; culms filiform, 3-angled, 6' -12' high; leaves and elonr 

 gated involucre very nan-ow. — Margins of ponds and streams, Florida to North 

 Carolina. July- Sept. -^ Rays 1'- 2' long. Spikelets 4" -7" long. 



§ 2. CYPERUS Proper. Sli/le 3-ckfi: nut 5-angled: joints of the rachis 

 winged by the adnate decurrent scales, rarely wingless. 



1. Spicati. Umbel simple or compound: spikelets few -many-flowered, distinct, 

 spreading, forming loose or compact spikes at the summit of the rays : scales rigid, 

 i-U-nerved: joints of the rachis commonly conspicuously winged: stamens 3. 



