Rhizomatous perennial, lax and tending to creep at the base, 1.5-7 dm, somewhat hirsute; lvs all petiolate, with cordate-ovate or triangular-ovate, crenate- serrate blade 1.5-6 נ1-5 cm, generally with an irregular broad white stripe about the midvein; verticils several, less crowded than in no. 3 [Lamium purpureum L.], the lower subtended by full-sized lvs, the upper by smaller and less petiolate ones; cal 5-10 mm, with firm, unequal, somewhat divaricate slender lobes; cor pink-purple (white), 2-3 cm, the tube curved, hairy outside and with a ring of hairs inside, the upper lip 7-12 mm, the lateral lobes each with a single terminal tooth; 2n=18. Native of Europe and adj. Asia, escaped from cult. on roadsides and waste places; e. Can. to Va. and W.Va. Apr.-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.