Our only specimen was found in a moist place near the crest of a high wooded slope along the Ohio River about 3 miles east of Elizabeth in Harrison County, and near the road leading up the bluff from Stuart's Landing. This species was reported in Coulter's Catalogue for Wilson from Hamilton County. Since this species much resembles Thaspium barbinode which, no doubt, is more or less frequent in Hamilton County and which was not reported by Wilson, and since the habitat of Ligusticum canadense does not occur in Hamilton County, there is little doubt but Wilson made an error in determination. I have not been able to locate Wilson's specimens. I never received answers to the letters I sent him.
Stout, freely branched, to 15 dm; lower lvs 3-4 times ternately compound, the upper less so and the uppermost sometimes simple; lfls thin, lanceolate to oblong or ovate, 3-8 cm, acute or acuminate, sharply serrate, broadly acute to rounded at base; terminal umbels often doubly compound, the primary rays to 2 dm, the secondary 2-5 cm, the pedicels 2-4 mm; fr elliptic, 5-7 mm, half to two-thirds as wide, the ribs narrowly winged; 2n=22. Woods, chiefly in the mts.; Pa. and Ky. to Ga. and Ala.; s. Mo. and Ark. June, July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.