A western sp., is intr. at St. Louis and may be expected in our region. It differs from both of the following spp. in its narrow, linear-oblanceolate or narrowly cuneate lvs 4-10 times as long as wide, less than 1 cm wide, with 1-3 teeth on each side toward the summit.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.