Fls in elongate, long-peduncled, interrupted spike-like racemes terminating the stem and also arising from a few upper axils; cal 2-lipped, the upper 3 lobes subulate, about equaling the tube, the lower 2 very short, broadly triangular; cor-tube scarcely widened upward, the upper lip straight, concave, emarginate, the lower much longer, spreading, 3-lobed; stamens 4, paired, included; ovary obliquely cylindric, with a single locule and a single erect, orthotropous ovule; style elongate, obliquely terminal; stigma 2-lobed; fr an achene, contained in the persistent cal, this closely reflexed against the axis, its upper lobes becoming hooked at the tip and indurate; simple-lvd perennial herbs. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.