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.

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).

Duration: Perennial Lifeform: Forb/Herb General: Perennial, 20-150 cm tall, sometimes taller; stems erect and stout or twining and reclining; roots tuberous. Leaves: Cauline, alternate, palmately cleft into 3-5 segments, 5- 15 cm wide, the segments narrowly elliptic, lanceolate, or linear in outline, blades glabrous to finely pubescent, margins of the ultimate segments variously cleft and toothed; blades petiolate. Flowers: Inflorescence a raceme, mostly 10-20 flowered, the flowers bilateral, nodding; pedicels 2-9 mm long; sepals 5, ovate, 1-4 mm long; petals 5, 4-9 mm long, greenish, cream-white, or pink; stamens 10, the anthers juxtaposed on the upper side of the flower; style elongate, 5.5-9 mm long, curved, exserted from the corolla; flowers July- August. Fruits: Aggregate of follicles, oblong, 1-2 cm long, beaked; seeds numerous. Ecology: Streambanks, meadows, seeps, coniferous forests, moist soils; 1100-3200 m (3500-10500 ft); Apache, Cochise, Coconino, Greenlee, Navajo, and Pima counties; western U.S., northern Mexico. Notes: Ours, as here described, is ssp. columbianum. Aconitum can appear quite similar to Delphinium. Aconitum has hooded upper sepals and usually 2 petals, whereas Delphinium has spurred upper sepals and usually 4 petals. Moonkshood is a highly toxic plant that should be handled with extreme care. Editor: Springer et al. 2008