Mem. New York Bot. Gard. 1: 155. 1900.
Stems 35-70(-100) cm; base ± reddish, glabrous, glaucous. Leaves cauline, 6-22, absent from proximal 1/5 of stem at anthesis; petiole 1-10 cm. Leaf blade pentagonal to round, 2-9 × 3-14 cm, margins seldom laciniate, nearly glabrous; ultimate lobes 5-17, width 2-8 mm, tips abruptly tapered to mucronate apex; midcauline leaf lobes more than 3 times longer than wide. Inflorescences 10-25-flowered; pedicel 0.5-1.5 cm, puberulent to glabrous; bracteoles 2-20 mm from flowers, green, linear, 3-8 mm, nearly glabrous. Flowers: sepals dark blue, nearly glabrous, lateral sepals spreading to reflexed, 8-12 × 3-4 mm, spurs straight, ascending 40-90°, 9-13 mm; lower petal blades ± covering stamens, 3-5 mm, clefts 1-2 mm; hairs centered, mostly near base of cleft, white. Fruits 7-13 mm, 3.4-4 times longer than wide, puberulent. Seeds ± wing-margined; seed coat cells narrow but short, surfaces smooth.
Phenology: Flowering summer.
Habitat: Rocky slopes in subalpine coniferous woods
Elevation: 2000-4000 m
Idaho, Mont., Wyo.
Hybrids with Delphinium glaucum are known.