Erect, rhizomatous perennial 6-10 dm, branched above; lvs thin, lacking translucent glands or superficial dots, oblong or elliptic-oblong to elliptic-oblanceolate, 7-13 נ2-5 cm, obtuse or rounded above, usually tapering to an acute to truncate base; cymes few-fld, on peduncles to 12 mm; sep at maturity narrowly oblong, acute, 4-6 mm; pet 5-7 mm; fr 9-11 mm; styles 1 mm. Wooded swamps on the coastal plain; se. Va. to La., n. in the interior to s. Mo. and s. O. July-Sept. (T. longifolium; Hypericum t.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.