Has 5-merous fls, with the filaments arising from (or just outside) the sinuses of the 5-lobed disk (the disk lobes often emarginate). (T. ramosissima; T. pentandra, an illegitimate name)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.