CYPERACEAE (SEDGE FAMILY) 



177 



219. C. erythrorkizos. 



220. C. ferax. 



19. C. erythrorhizos Muhl. Annual i culm obtusely 

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

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

 spikelets very numerous, crowded in oblong or cylindrical 

 nearly sessile heads, spreading horizontally, linear, flat- 

 fish (3-10 mm. long}, bright chestnut-colored; scales 

 lanceolate, mucronulate. ( C. Halei 

 Britton, in part, not Torr.) Allu- 

 vial banks, Mass, to Ont., Minn., 

 and south w. FIG. 219. Dwarf 

 tufted plants are sometimes sepa- 

 rated as Var. PUMILUS Engelm. 



20. C. fdrax Rich. Culm stout, 

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



of the simple or compound umbel mostly all short and 

 crowded ; spikelets 10-2Q-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. Engelmanni Steud. Similar ; but the spikelets more slender and terete, 

 somewhat remotely b-lb-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. strig&sus 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 

 222. C. strigosus. 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. 

 CAPITA-PUS Boeckl. 



Var. robustior Kunth. Spikelets 2-3 cm. long. Local, 

 Mass, to Fla. and Mo. 



Var. comp6situs Britton. Umbel compound; spikelets 0. 5- 

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

 La., and la. 



23. C. refractus 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-G-floicered, 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. lancastriensis Porter. Culm stoutish, triangular, 

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



3f C-9 mostly elongated rays : spikelets very numerous in 223. C. refractus. 



GRAY'S MANUAL 12 



221. C. Engelmanni. 



