CYFERACE.fi. ^SEDGE FAMILY.) 493 



10. C. acusniafatus, Torr. Slender (3' -12' high) ; spikes ovate, becom- 

 ing oblong, 16-30-flowered, pale, collected in simple or compound heads; scales 

 obscurely 3-nenrd, their short acute tips somewhat spreading ; achenium obloug, 

 pointed at both ends. — Low ground, Illinois and westward. 



# * # Hoot perennial: stamen only 1 : spikes short and flat, ovate and oblong, crowd- 

 ed in close globular heads ; the joints of the axis not margined. 



11. G. V ire lis, Miehx. Culm (l°-4°high) either sharply or obtusely 

 triangular; leaves and involucre very long, keeled; umbel compound, many- 

 rayed ; achenium oblong or linear, £ to 1 the length of the narrow oblong aeut- 

 ish seal-. (0. vegetus, Torr.) — Wet places, Virginia and southward. — Heads 

 of spike-; green, turning tawny. 



■J? * «• # Root perennial : rootstocks creeping, or tuberous: stamens 3. 



-«- Spikes flat, closely flowered, ovate-oblong or becoming broadly linear, 3-5 at the 



end of each ray of the compound umbel. 



12. C. tleatatUS, Torr. Culm slender (6' -12' high) ; umbel 4-7-rayed; 

 spikes 6 - 30-flowcred ; scales strongly keeled, and with abruptly sharp-pointed 

 slightly spreading tips, reddish-brown on the sides, green on the back ; achenium 

 obovate, sharply triangular. — Sandy swamps, Massachusetts to Virginia, and 

 southward. Aug — Spikes 2"- 5" long, sometimes changing into leafy tufts, 

 -i- ->- Spikes flat, closely flowered, linear {§' - V long), loosely spiked along the upper 



part of the rays of the open umbel : rootstocks slender, creeping extensively, and 

 bearing small nut-like tubers. 



13. C. rotiandus, L., var. Hydra. (Nut-Grass.) Culm slender 

 (£°-l£° high), longer than the leaves; umbel simple or slightly compound, 

 about equalling the involucre; the few rays each bearing 4-9 dark chestnut- 

 purple 12-40-fiowercd acute spikes ; scales ovate, closely oppressed, nerveless except 

 on the green keel. (C. Hydra, Michx.) — Sandy fields, Virginia and south- 

 ward : probably an immigrant from farther south. Excessively troublesome to 

 planters. (Eu.) 



14. €. phyiuatodes, Muhl. Culm (1° -2^° high) equalling the leaves; 

 umbel often compound, 4- 7-rayed, much shorter than the long involucre ; spikes 

 numerous, light chestnut or straw-color, acutish, 1 2 - 30-flowered ; scales oblong, nar- 

 rowly scarious-margined, nerved, the acutish tips rather loose ; achenium oblong. 

 (C. repens, Ell.) — Low grounds, along rivers, &c, Vermont to Michigan, Illi- 

 nois, and common southward. Aug. — Tubers small, at the end of very slender 

 rootstocks : by these the plant multiplies rapidly, and becomes a pest. 



■*-+-•*- Spikes flattish. rather loosely flowered, greenish, lance-linear, capitate-clus- 

 tered {except in No. 15) ; the convex ovate scales mauy-ncrved, only § or { longer 

 than the triangular achenium: culms tufted from hard tuberiferous rootstocks. 

 15. -C. ScllweiilStzii, Torr. Culm rough on the angles (1°- 2° high) ; 

 leaves linear ; umbel simple, 4 - 8-rayed ; spikes crowded at the upper part of the 

 mostly elongated rays, erect, loosely 6 - 9-flowered, a bristly bract at the base of 

 each ; scales awl-pointed, scarcely longer than the ovate achenium ; joints of the 

 axis narrowly winged. — Dry sandy shores, &c, Lake Ontario, New York, to 

 Illinois, and northwestward. Aug. — Spikes %'-£' long: the scales large ia 

 proportion. 



