CYPERACEjE. (SEDGE FAMILY.) 493 



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

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

 obscurely 3-nerved, their short acute tips sometc/tat spreading ; sichcnium oblong, 

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



# # *- Root 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. C. vil'CllS, Michx. Culm (l-4high) cither 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 oblcng acut- 

 ish scale. (C. vegetus, Torr.) Wet places, Virginia and southward. Head* 

 of spikes green, turning tawny. 



# # # # Root perennial : rootstocks creeping, or tuberous : stamens 3. 



-i- Spikes flat, closely flowered, ovate-oblong or becoming broadly linear, 3-5 at tfu 



end of each ray of the coiujwund umbel. 



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

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

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

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

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

 - +- Sjiikes flat, closely flowered, linear (^' - 1' long), loosely spiked along the upper 



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

 bearing small nut-HLe tubers. 



13. C. rot ("nidus, 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 \ 2 - 40-flowered 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. C. pliyiliatddes, Muhl. Culm (l-2^ high) equalling the leaves ; 

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

 numerous, light chestnut or straio-coJor, acutish, 12 30-flowercd; scales ol-lonn. nar- 

 Toii'li) scarious-margined, nerved, the acutish tips rather loose ; achenitim 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 flatfish, rather loosely flowered, greenish, lance-linear, capitate-clus- 

 tered (except in No. 15); the convex ovate scales wainj-nerced, on/// | or j longer 

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



15. C. Sclivveinlfzii, Torr. Culm rough on the angles (l-2 high) ; 

 leaves linear; umbel simple, 4-S-rnyed; spikes croicdc-d at the upper part of the 

 mostly elongated rays, erect, loosely 6 - 9-flowercd, 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 nortl westward. Aug. Spikes ;}'-?' long: the scales large in 

 proportion. 



