Stout, to 2 m, becoming tomentulose-canescent in the infl; principal lvs long-petioled, 1-2 dm, the upper reduced, with sheathing petioles; lfls oblong to elliptic, varying to lanceolate, 2-4 cm, obtuse, finely serrate; umbels 5-15 cm wide, rays 18-35; pedicels and ovary pubescent; fr oblong-elliptic, 4-7 mm, cordate at base, sparsely pubescent along the wingless dorsal ribs; lateral ribs winged; oil-tubes few; seed adherent to the pericarp; 2n=22. Dry woods and thickets; Mass. to Minn., s. to Fla., Miss., and Ark. July-Aug. (A. villosa Walter, not Lag.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.