Roots tuberous, tuber distally not obviously bulblike, to 60 × 15 mm, parent tuber producing 1 (rarely 2) daughter tubers with connecting rhizome very short, i.e., tubers ±contiguous. Stems erect and stout to twining and reclining, 2-30 dm. Cauline leaves: blade deeply 3-5(-7)-divided, usually with more than 2 mm leaf tissue between deepest sinus and base of blade, 5-15 cm wide, segment margins variously cleft and toothed. Inflorescences open racemes or panicles. Flowers commonly blue, sometimes white, cream colored, or blue tinged at sepal margins, 18-50 mm from tips of pendent sepals to top of hood; pendent sepals 6-16 mm; hood conic-hemispheric, hemispheric, or crescent-shaped, 11-34mm from receptacle to top of hood, 6-26 mm wide from receptacle to beak apex.
B.C., Ariz., Calif., Colo., Idaho, Iowa, Mont., N.Mex., N.Y., Nev., Ohio, Oreg., S.Dak., Utah, Wash., Wis., Wyo., Moist areas, primarily in w North America, sporadic in e U.S.
Subspecies 2 (2 in the flora).
Available information suggests that Aconitum columbianum is probably not one of the extremely toxic aconites (D. E. Brink 1982; J. D. Olsen et al. 1990).