Cal deeply 5-parted, regular, its lobes broadly elliptic, obtuse or rounded above; cor bilabiate, the upper lip shallowly 2-lobed or emarginate, arched, the lower shortly
3-lobed, the middle lower lobe elevated into a villous palate nearly or quite closing the throat; fertile stamens 4, inserted at the base of the cor, the filaments flat, villous, the anthers densely villous- tomentose; sterile stamen much shorter and narrower, glabrous; fr septicidal; seeds flat, suborbicular, with a broad wing; perennial herbs, simple or sparingly branched, with glabrous stem and large, opposite, serrate, usually glabrous lvs; fls large, white to pink or purple, in dense spikes terminating the stem and branches, each fl closely subtended by 2 or 3 large, sep-like bracts. 4, e. N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.