CYPEBACEAE (SEDGE FAMILY) 



201 



alba. 



to Alaska, s. to Fla., Ky., the Great Lake region, and n. Cal. 

 July-Sept. (Eurasia, Porto Rico.) FIG. 323. Var. M.\CR.V Clarke. 

 Coarser, 4-8 dm. high ; terminal corymb often 2-4 cm. broad. 

 The common southern form, extending n. to central N. Y. and Mass. 



** ** Spikelets chestnut-colored, f ew-several-flower ed ; 

 stamens 3 ; bristles usually 6. 



12. R. capillacea Torr. Culm 1-4.5 dm. hi<:h, 

 slender; leaves bristle-form; spikelets 3-6 in a ter- 

 minal cluster, and commonly 1 or 2 on approximate 

 or remote axilliary peduncles, oblong-lanceolate (pale 

 chestnut-color); achene oblong-ovoid, stipitate, very 

 obscurely wrinkled, about half the length of the (6, rarely 12) 

 stout bristles, and twice the length of the lanceolate-beaked 

 824 R caniiiacea tubercle. Marly bogs and wet limestone rocks, e. Que. to 

 w. Ont., s. very locally to N. J., Pa., O., Mich., and Mo. July- 

 Sept. FIG. 324. Var. LEVISETA E. J. Hill. Bristles perfectly 

 smooth. Local, Me., Ont., Mich., and Ind. 



13. R. Knieskernii Carey. Culm 1-6 dm. high, slender ; 

 leaves narrowly linear, short ; spikelets numerous, crowded in 

 4-6 distant clusters, oblong-ovoid, 2-3 mm. long ; achene obovoid, 

 narrowed at base, equaling the bristles, twice the length of the 

 triangular flattened tubercle. Pine-barrens of N. J. (on bog 

 iron ore exclusively) to Va. ; rare. July-Sept. FIG. 325. 



14. R. glomerata (L.) Vahl. Culms 0.1-1 m. high ; leaves 



linear, flat; spikelets numerous in distant clusters or heads (0.5-1.5 cm. broad) 

 often in pairs from the same sheath, ovoid-oblong; achene 

 obovoid, margined, narrowed at base, as long as the lance- 

 awl-shaped flattened tubercle, which equals the always down- 

 wardly barbed bristles. Low grounds, N. B. to Ont., and 

 southw. July-Sept. FIG. 326. Var. nisctTiEss Clarke. 

 Bristles barbed only at the tip or quite smooth. 

 N. J., and southw. 



Var. paniculata (Gray) Chapm. Coarse 

 and tall (1-2 m.); the very elongate inflores- 

 cence bearing numerous loose clusters of 

 heads. Md. and Ind., southw. 



15. R. axillaris (Lam.) Britton. Culm 

 stout (0.4-1.2 m. high); leaves narroidy 

 linear, flat, keeled; spikelets very numerous, crowded in 2 or 3 

 or more dense globular heads (1.5-2.5 cm. thick), which are dis- 

 tant (and often in pairs), oblong-lanceolate, dark brown ; achene 

 orbicular-obovoid, margined, narrowed at base, 2-2. 5 mm. long, 

 about as long as the awl-shaped beak ; bristles twice longer, 

 stout, barbed downward and sometimes also upward. (E. cephalantha Gray.) 

 Sandy swamps, L. I. and N. J. to Fla. and La. Aug.-Oct. FIG. 327. 



Var, microc&phala Britton. More slender, and usually lower ; glomerules 

 0. 7-1.5 cm. thick ; achenes smaller. N. J. to Fla. and La. 



825. It. Knies- 

 kernii. 



826. R. glomerata. 



827. R. axillaris. 



15. CLADIUM P. Br. TWIG RUSH 



Spikelets ovoid or oblong, of several loosely imbricated scales ; the lower 

 empty, one or two above bearing a staminate or imperfect flower ; the terminal 

 flower perfect and fertile. Perianth none. Stamens 2. Style 2-3-cleft, decidu- 

 ous. Achene ovoid or globular, somewhat corky at the summit, or pointed, 

 without any tubercle, in which it differs from Eynchospora. (Diminutive 

 of (cXdSos, a branch, from the repeatedly branched cyme of the original 

 species.) 



1. C. mariscoides (Muhl.) Torr. Perennial; culm obscurely triangular 



