Plants perennial, from large, fleshy rhizomes. Stems 1 or more, mostly 5-10 dm. Leaves ca. 3, compound, 10 cm or more; blade with 3 orders of leaflets and lobes; ultimate lobes broadly elliptic or less commonly ovate to obovate with rounded apex, sometimes narrowly elliptic with acute apex, 1-8 × 0.5-4 cm, minutely apiculate. Inflorescences axillary or terminal, racemose or paniculate, 15-35-flowered on primary axis; bracts inconspicuous, proximal bracts narrowly elliptic, distal linear and much reduced. Flowers erect; pedicel 2-5 mm; sepals caducous, ovate to broadly lanceolate, 1-2 mm, margins lacerate or dentate; petals light to deep pink; spurred petal usually somewhat curved, 20-25 mm, spur lanceoloid, 14-20 mm, crest well developed, usually exceeding petal apices, marginal wing absent; unspurred outer petal boat-shaped, 12-15 mm; inner petals not tipped deep red or purple, usually 9-11 mm, blade much wider at apex, claw slender, equaling blade in length; nectariferous spur 1/2-2/3 length of petal spur, bent or hooked at apex; style ca. 3 mm; stigma roughly triangular, with 2 apical and 2 lateral papillae. Capsules reflexed, obovoid, 10-15 × 4-5 mm. Seeds ca. 3.5 mm diam., with numerous small protuberances. 2 n = ca. 130.

Flowering mid spring-early summer. Moist, shady woods, particularly along streams; 0-1100 m; B.C.; Oreg., Wash.

Corydalis scouleri is restricted to cool, wet habitats from northwestern Oregon northward to Vancouver Island. It is most easily distinguished from Corydalis caseana by the usually highly developed crests and absence of wings on its outer petals. The stigma is essentially triangular (versus rectangular in C . caseana ), and the capsule shape (typically obovoid) is rarely approached in C . caseana .