Fibrous-rooted perennial 3-6 dm; lvs mostly basal, long-petioled, ovate- oblong, 7-12 cm, irregularly serrate or crenate; cauline lvs few, smaller; racemes 1-2 dm, interrupted; fls 4-8 per node, the bracteal lvs broadly ovate, green, mostly under 1 cm; cal villosulous, the upper lip broadly ovate, minutely 3-toothed, two-thirds as long as the tube, and much shorter than the acute or aristate lobes of the lower lip; cor blue (1.5-)2-3 cm (smaller in pistillate fls), the upper lip arched into a half-circle and laterally flattened; 2n=18. Native of s. and c. Europe, occasionally found as a weed in fields and pastures in our range. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.