Cal tubular, 15-nerved, 2- lipped, the uppermost lobe much wider than the other 4; cor weakly 2-lipped (in ours), the elongate tube gradually widened distally, the limb much shorter; upper lip straight, emarginate, and subgaleately rounded, the lower lip 3-lobed, with the large central lobe sometimes 2- cleft; stamens 4, ascending under the upper lip, the upper pair slightly the longer; pollen- sacs divaricate at a wide angle, confluent in dehiscence; nutlets oblong, smooth; erect herbs with serrate lvs and verticils of small blue fls. (Moldavica) (Name often misapplied to Physostegia) 40, N. Hemisphere.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.