Annual from a short taproot, often branched at base, decumbent or nearly prostrate, inconspicuously hairy, the stems 1-4 dm; lvs all petiolate, crenate or crenate-serrate, the lower with rotund-cordate or broader blade 0.7-3 cm and separated by 1-3 very elongate internodes from the several more ovate-cordate, closely crowded, shorter-petiolate, and eventually smaller upper pairs which subtend the verticils of fls; cal 5-6 mm, with firm, unequal, somewhat divaricate slender lobes about as long as the tube; cor pink-purple, mostly 1-1.5 cm, the tube straight, hairy outside and with a ring of hairs inside near the base; upper lip 2-4 mm; 2n=18. Native of Eurasia, now established as an occasional weed in fields, gardens, and waste places throughout much of our range and elsewhere in Amer. Apr.-Oct.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.