Cal regular, about 13-nerved, very villous in the throat, the lobes ovate-triangular; cor-tube scarcely widened distally, the upper lip straight, flat or nearly so, 2- lobed, the lower lip somewhat longer, deflexed, deeply 3-lobed; stamens 4, the lower pair well exsert, divergent from each other, the upper pair shorter, about equaling the upper lip; nutlets ovoid, smooth; perennial herbs with large, repeatedly trichotomous terminal infl, each node and each fl subtended by a subsessile oval bract, the upper bracts progressively smaller. 15, Eur. and Medit. reg. to c. Asia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.