CYPEKACEAE (SEDGE FAMILY) 



201 



. R. alba. 



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

 July-Sept. (Eurasia, Porto Rico.) FIG. 323. Var. M!CRA 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. 



.w t-c Spikelets chestnut-col or ed, few-several-flowered ; 

 A/K\ stamens 3 ; bristles usually 6. 



/O| 12. R. capillacea Torr. Culm 1-4.5 dm. high, 



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



\ m minal cluster, and commonly 1 or 2 on approximate 



w|P or remote axilliary peduncles, oblong-lanceolate (pale 



yjjj 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 

 004 P p-miihpp tubercle. Marly bogs and wet limestone rocks, e. Que. to 

 ' w. Ont., s. very locally to N. J., Pa,, 0., 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 1-0 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.) Valil. Culms 0.1-1 in. 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 

 south w. July-Sept. FIG. 326. Var. DISCUTIENS Clarke. 

 Bristles barbed only at the tip or quite smooth. 

 N. J. , and south w. 



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-L2 in. high); leaves narrowly 

 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, 327 i>. axillaris. 

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

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

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



Var. microcephala Britton. More slender, and usually lower ; glomerules 

 0.7-1.5 cm. thick ; achenes smaller. N. J. to Fla. and La. 



325. R. Knies- 

 kernii. 



R. glomerata. 



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 K\d8os, "a branch, from the repeatedly branched cyme of the original 

 species.) 



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



