CTPEUACEAE (SEDGE FAMILY) 



177 



219, C. erythrorhizos. 



220. C. ferax. 



19. C. erythrorhizos Muhl. Annual ; culm obtusely 

 triangular (1-8 dm. high) ; umbel many-rayed ; invo- 

 lucre 4-5-leaved, very long ; involuoels bristle-form ; 

 spikelets very numerous, crowded in oblong or cylindrical 

 nearly sessile heads, spreading horizontally, linear, flat- 

 tish (.'J-IO mm. lonrj), bright chestnut-colored; scales 

 lanceolate, mucronulate. (C Halei 

 Britton, in part, not Torr. ) — Allu- 

 vial banks, Mass. to Ont, Minn., 

 and southw. Fig. 219. — Dwarf 

 tutted plants are sometimes sepa- 

 rated as Var. ptMiLus Engelm. 



20. C. fSrax Rich. Culm stout, 

 mostly low (0.3-8 dm. high) ; rays 



of the simple or compound umbel mostly all short and 

 crowded ; spikelets 10-20-flowered, yellowish-brown or drab 

 at maturity (0.5-1.8 cm. long), the short joints of its axis 

 winged with very broad scaly margins which embrace the 

 ovoid-triangular achene; the firm scales ovate, obtusish, 

 overlapping. (C speciosus Vahl.)' — Low grounds and 

 sandy banks, Mass. to Fla., w. to Ont., Minn., and Tex. ; Cal. (Trop. re- 

 gions.) Fig. 220. 



21. C. Engelminni Steud. Similar; hut the spjfteZeis more sZeniJer and terete, 

 somewhat remotely Si-lo-flowered, the zigzag joints of the axis slender and nar- 

 rowly winged, and the oblong or oval broadly scarious 

 scales proportionally shorter, so as to expose a part of the 

 axis of each joint; achene oblong-linear, very small. — 

 Low grounds, Mass. to Wise, 

 and southw. Fig. 221. 



22. C. strigbsus L. Peren- 

 nial, with hard corm-like 

 tubers ; culm 0.1-1 m. high ; 

 leaves flat, soft ; most of the 

 rays of the simple or com- 

 pound umbel elongated, their 

 sheaths 2-bristled ; spikelets 

 several-flowered, 0.7-1.8 cm. 



long, spreading, in loose heads ; scales oblong- 

 lanceolate, appressed, several-nerved, much longer 

 than the linear-oblong achene. — Damp or fertile 

 soil, Me. to Ont., Minn., southw. and westw. Fig. 

 222. — Very variable; dwarf plants with the rays scarcely developed are Var. 

 capitXtus Boeckl. 



Var. robiistior Kunth. Spikelets 2-3 cm. long. — Local, 

 Mass. to Fla. and Mo. 



Var. comp6situs Britton. Umbel compound; spikelets 0.5- 

 L3 cm. long, in dense cylindric heads. — Local, Mass. to Fla. , 

 La., and la. 



23. C. refrdctus Engelm. Culm smooth, 3-9 dm. high ; 

 leaves soft and flat, 4-8 mm. broad, slightly scabrous ; rays 

 usually more or less elongated, smooth ; spikelets very slender, 

 acuminate, subterete, in rather loose heads, divaricate or more 

 or less reflexed, 2-6-flowered, 1-3 cm. long; scales appressed, 

 several-nerved, the lower empty and often persistent after the 

 fall of the rest ; joints of the rhachilla winged, inclosing the 

 linear achene. — Dry woods and banks, N. J. to Ga. and Mo. 

 Fig. 223. 



24. C. lancastrifinsis Porter. Culm stoutish, triangular, 

 smooth, 3-8 dm. high; leaves rather broad (0.5-1 cm.) ; umbel 

 of 6-9 mostly elongated rays ; spiJcelets very numerous in 228. o. refractus. 



2;il. C Engelmanni. 



C. strlgosQS. 



