Annual; stems erect, 3-8 dm, softly villous, especially above; cauline lvs alternate, sessile, broadly ovate to elliptic or obovate-oblong, 4-10 cm; lvs subtending the 3-rayed infl whorled or sometimes merely opposite, those within infl smaller, margined with white or wholly white; cymes crowded; involucres hairy, the 5 lobes deeply fimbriate, the 5 appendages white, conspicuous, reniform to broadly ovate; fr 3-lobed, 6-7 mm thick; seeds ovoid, 4 mm, tuberculate; 2n=56. Prairies and plains; Minn. to Mo., w. to Mont. and N.M., and escaped from cult. elsewhere. Summer. (Dichrophyllum m.; Lepadena m.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
