Heracleum lanatum Michx.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Robust, single-stemmed perennial 1–3 m, generally ± pubescent or even tomentose; lvs once ternate, with broad, petiolulate, coarsely toothed and palmately lobed lfls mostly 1–3(–4) dm long and wide, the lateral ones mostly narrower than the central and often asymmetrical; terminal umbel commonly 1–2 dm wide at anthesis, with mostly 15–30 rays; bracts 5–10, narrow, deciduous; fr on pedicels 8–20 mm, obovate to obcordate, 7–12 mm, often pubescent; 2n=22. Rich damp soil; Lab. to Alas. and Siberia, s. to Ga. and Ariz. June, July. (H. sphondylium ssp. montanum, as to Amer. plants; H. maximum)