Plants , 3-5 dm. Leaves: petiole 1-3 cm. Central leaflet blade ca. 7-16 × 8-17 cm, proximal margins entire, distal margins (3-)6-9(-12)-lobed. Inflorescences 2.8-5.8 cm excluding peduncle. Flowers: stamens 3.8-6 mm; ovaries 1.5-2 mm. Follicles brown, 3.5-5 mm. 2 n = 24. Flowering spring-summer (Apr-Jul). Coastal and mountainous regions, Sequoia sempervirens and Pseudotsuga menziesii forests; 0-1200 m; B.C.; Calif., Oreg., Wash. Triploid plants have been reported from one locality in central Washington and from a site in northwestern California.