Branching annual 3-10 dm; lvs petioled, ovate to lanceolate, 3-7 cm, acute or short-acuminate, crenate-serrate, tapering to the base; spikes 2-5 cm; bracts rotund, 3 mm, cuspidate, ciliate, closely imbricate, each subtending 2 or 3 pale blue fls 4 mm; cor villous around the lips. Native of Asia, established in moist soil from Que. to N.Y. and N.J., and sometimes inland to Wis. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.