Stems 2-4 dm, erect or lax, sometimes scrambling or almost twining; scale-lvs mostly alternate, or the lower opposite; infl usually paniculate, commonly 5-10(-25) cm, the slender pedicels arcuately ascending or divergent; fls 2.5-4 mm; sep lance-subulate, 2-2.5 mm, distinct; pet lanceolate, long-acuminate; anthers yellow, blunt; 2n=52. Swamps, bogs, and wet meadows; Nf. to Fla. and Miss., along the coast, or on the coastal plain, n. in the interior to Ky., Mo., and Okla.; isolated in n. Mich. and s. Ont. Late summer. (B. lanceolata) Our plants are mostly var. paniculata, as described above. Plants from N.S. and s. even to Mass. often diverge toward the otherwise more northern var. iodandra (Rob.) Fernald, which has the sep connate below, the pet blunter, and the anthers often purplish. Such intermediate plants have been called var. intermedia Fernald.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.