CYPERACE^E. (SEDGE FAMILY.) 585 



chestnut-color) ; achene obovate t half the length of the bristles, equalling the tri- 

 angular-sword-shaped acute tubercle, which is rough-serrulate on the margins. 

 Low grounds, N. Brunswick to N. J., west to L. Superior. (Eu.) 



5. R. gracilenta, Gray. Culms very slender, 1-2 high; leaves nar- 

 rowly linear ; spikelets ovoid, in 2 - 4 small clusters, the lateral long-peduncled ; 

 achene ovoid, rather shorter than the bristles, about the length of the flat awl- 

 shaped tubercle. Low grounds, southern N. Y. and N. J. to Fla. 



6. R. oligantha, Gray. Culm and leaves filiform, 6-12' high; spike- 

 \ets very few (1 -4), ovate-oblong; bristles plumose below the middle ; achene 

 bovate-oblong, bearing a conical tubercle ^ its length. Del. (Canby) to Fla. 



-t- H- Bristles none, or 1-3 and minute ; spikelets pale, I flowered. 



7. R. pallida, M.A.Curtis. Culm (1-2 high) acutely triangular; 

 leaves and spikelets as in the next species, but only a terminal dense cluster, 

 which is less white or turns pale reddish-tawny ; achene obovate-lenticular, 

 tipped with a minute depressed and apiculate tubercle ; the delicate bristles 

 4-5 times shorter or obsolete. Bogs in pine-barrens of N. J. and N. C. 



---(--t- Bristles long, denticulate downward, or both ways in n. 11. 



*+ Spikelets white or whitish, becoming tawny with age, perfecting only a single 



flower ; stamens usually 2 ; bristles 9-12, or even 20. 



8. R. alba, Vahl. Culm slender (1 -2 high), triangular above; leaves 

 narrowly linear or almost bristle-form ; spikelets lanceolate, densely crowded 

 in a head-like terminal corymb and usually one or two lateral ones ; achene 

 oblong-obovate with a narrowed base, scarcely longer than the flattened-awl- 

 shaped tubercle, shorter than the bristles. Bogs, Newf . to Fla., west to N. 

 Ind., Minn., and Oregon. (Eu.) 



- -w- Spikelets chestnut-colored or darker in n. 10 and 11, few -several-flowered ; 

 stamens 3 ; bristles usually 6. 



9. R. capillacea, Torr. Culm 6 - 9' high, slender ; leaves bristle-form; 

 spikelets 3-6 in a terminal cluster, and commonly 1 or 2 on a remote axillary 

 peduncle, oblong-lanceolate (pale chestnut-color, 3" long) ; 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 tubercle. Bogs and 

 rocky river-banks, N. Vt. to Penn., west to western N. Y. and Minn. Var. 

 LEVisiiTA, Hill. Bristles perfectly smooth. N. W. Ind. 



10. R. Kniesk&rnii, Carey. Culm 6 -18 7 high, slander; leaves nar- 

 rowly linear, short; spikelets numerous, crowded in 4-6 distant clusters, oblong- 

 ovate (scarcely 1" long) ; achene obovate, narrowed at base, equalling the bristles, 

 twice the length of the triangular flattened tubercle. Pine-barrens of N. J. 

 (on bog iron ore exclusively) to Va. ; rare. 



11. P. glomerata, Vahl. Culm 1-3 high; leaves linear, flat; spike- 

 lets numerous in distant clusters or heads (often in pairs from the same sheath), 

 ovoid-oblong ; achene obovate, margined, narrowed at base, as long as the lance- 

 awl-shaped flattened tubercle, which equals the always downwardly barbed 

 bristles. Low grounds, N. Eng. to Fla., west to Mich, and N. Ind. 



12. R. cephalantha, Gray. Culm stout (2-3 high); leaves narrowly 

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

 globular heads which are distant (and often in pairs), oblong-lanceolate, dark 



