Cal irregularly 10-nerved, bilabiate, the upper lip broad, shallowly 3-toothed, the lower deeply cleft into 2 narrow segments; cor bilabiate, the upper lip galeate-hooded and entire or nearly so, the lower shorter and 3-lobed; cor-tube with a ring of hairs inside; stamens 4, ascending under the galea, the lower pair the longer, scarcely exserted; filaments ±bidentate at the tip, the anther borne on the lower tooth; pollen-sacs set end to end on the expanded connective, separately dehiscent; nutlets smooth; perennial herbs with blue or purple to white fls crowded into a dense, evidently bracteate terminal spike, the bracts sharply differentiated from the lvs. 4, cosmop. (Brunella)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.