176 



CYPEKACEAE (SEDGE FAMILY^ 



212. 0. fascus. 



3-nerved. (O. calcaratus Nees.) — Wet places, Del. to Fla. and Tex. ; northTV 

 in the flat country to Mo. and Kan. Tig. 211. 



13. C. Fuscus L. Low (1-3 dm. high) ; spikelets linear, 3-8 mm. long, the 



thin brown scales (greenish 



(inly on the keel) very faintly 



nerved ; stamens 2 ; aclienes 



equaling the scales. — Locally 



on ballast, Mass. to N. J. 



(Adv. from Eu.) Fig. 212. 

 14. C. Mspan L. Culms 



sharply angled (2-8 dm. 



high) ; leaves linear, often 



reduced to membranous 

 sheaths ; umbel spreading, the filiform rays mostly longer 

 than the 2-leaved involucre ; spikelets narrowly linear ; 

 scales light reddish-brown, oblong, mucronate, 3-nerved ; ^jg g haspan 



wings of rhaohilla persistently attached ; achenes round- 

 obovoid. — Ponds and ditches, Va. to Fla. and Tex. Fig. 213. 



15. C. dentJltus Torr. Perennial by slender rootstocks 

 and tuber-bearing stolons; culms slender (1-6 dm. high) ; 

 leaves rigid and keeled ; umbel erect, shorter than the 3-4- 

 leaved involucre ; spikelets 5-13-flowered ; scales reddish- 

 brown, with green keel, ovate, acute, 1 -nerved, 

 the mucronate tips prominent. — Sandy shores, 

 Me. to N.Y., and southw. — Spikelets often 

 abortive and changed into leafy tufts. Fig. 

 214. 



Var. cten(5stachys Fernald. Spikelets 15- 

 40-flowered ; scale-tips less prominent. — Mass. 

 to N. J. Fig. 215. 



16. C. rotiindus L. (Nut Ghass.)* Peren- 

 nial by tuber-bearing stolons ; culm slender (1-6 dm. high), longer than the 



leaves ; umbel simple or slightly compound, about 

 equaling the involucre ; the few 

 rays each bearing 4-9 dark chest- 

 nut-purple 12-40-flowered acute 

 spikelets (0.8-2.5 cm. long) ; scales 

 ovate, closely oppressed, nerveless 

 except on the keel ; achenes linear- 

 oblong. — Sandy fields, Va. to 

 Fla. and Tex. ; also adv. near 

 Phila. and N. Y. City. (Trop. and 

 subtrop. regions.) Fig. 216. 



17. C. Hdllii Britton. Similar ; 

 culm stout, 4-9 dm. high, scarcely 

 exceeding the broad (0.5-1 cm.) 

 leaves ; umbel compound, the 

 numerous rays much exceeded by 

 the involucral bracts; spikelets chestnut-purple, 1-1.5 cm. 

 scopes distinctly nerved. — Kan. to Tex. 



18. C. esculfintus L. Similar ; culms (3-9 dm. high) equaling the leaves ; 

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

 lets numerous, light chestnut or straw-color, acutish, 0.5-1.5 

 cm. long ; scales ovate or ovate-oblong, narrowly scarious- 

 margined, nerved, the acutish tips rather loose ; achene 

 oblong-obovoid. — Low grounds, along rivers, etc. ; spreading 

 extensively by its small nut-like tubers and sometimes! 

 becoming a pest in cultivated grounds. (Eurasia.) Fig. 217. 

 Var. leptostXchyus Boeckl., with spikelets 1.8-3.5 cm. long, is less frequent. 

 Fig. 218. 



214. 0. dentotuB. 



215. 0. dentatus, 

 V. ctenostachys. 



216. C. rotundas. 



217. 



long; 



C. esculentus. 



the acutish 



218. C. esculentuB, 

 V. leptostachyus. 



