Much like no. 1 [Petasites frigidus (L.) Fr.], but the basal lvs triangular-ovate, cordate or more commonly sagittate at base, to 3 dm, pinnipalmately veined, merely dentate, with 20-45 teeth on each side, varying to merely a little wavy and callous-denticulate; bracts of the stem averaging longer and narrower, more often with abortive blade; rays mostly a little longer, commonly 8-9 mm; 2n=58-60. Wet places; Lab. to Alas., s. to Wis., Minn., S.D., and Wash. May, June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.