CYPERACEAE (SEDGE FAMILY) 



177 



219. C. erythriirlii/.tis. 



19. C. erythrorhizos Mulil. Annual ; 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- 

 tish (3-1 it mm. long), bright chestnut-colored; scales 

 !<incp.olate,mucronulate. (C. Halei 

 Britton, in part, notTorr. ) Allu- 

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

 and southw. FIG. 219. Dwarf 

 tufted plants are sometimes sepa- 

 rated as Var. pfjMiLus Engelm. 



2i>. C. fdrax Rich. Culm stout, 

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



of the simple or compound umbel mostly all short and 

 crowded ; spikelets I0-'20-flowered, yellowish-brown or drab 

 at maturity (0.6-1.8 cm. long), the short joints of its axis 

 winged with very broad scaly margins which embrace the 

 C ferax. 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 ct-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 conn-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 strigosuB tnan ^e 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. 

 CAPITXTCS 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. 



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 ; sjnkelets very slender, 

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

 or less reflexed, 2-6-floioered, 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. 3. to Ga. and Mo. 

 FIG. 223. 



24. C. lancastrie'nsis Porter. Culm stoutish, triangular, 

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

 of G-9 mostly elongated rays ; spiJcelets very numerous in 223. C. refractus. 



GRAY'S MANUAL 12 



'2*21. C. Engeluianni. 



