Perennial, 3-8 dm; stem thinly strigose above; cauline lvs mostly 4-5 pairs, lanceolate or lance-oblong, 5-10 cm נ8-12 mm, acute, sessile or the lowest petiolate; infl openly paniculate, much branched; fls rose-purple or sometimes white; cal 6-10 mm, campanulate, glabrous except for the densely ciliate short lobes; pet 15-20 mm, without auricles, the appendages 2-3 mm, dissected, the blade 8-12 mm, deeply 2-lobed, the lobes oblong-linear, with a pair of slender lateral teeth, or dissected; fr 5-7 mm; 2n=24. Native of Europe, frequently escaped from cult. in our range. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.