Cal 15-nerved, regular or 2-lipped at anthesis, in fr enlarged, indurate, and evidently 2-lipped; cor very irregular, the tube long-exsert, widened from the middle to the summit, the 4 upper lobes about alike, the lower median lobe much longer, deeply fringed; stamens 2 or 4, divergent, long-exsert, the pollen-sacs widely divergent; nutlet usually solitary, globose, smooth; perennial herbs from a thick woody rhizome, with ample, petiolate, serrate lvs and terminal panicles of yellow or yellowish fls. 5, e. N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.