in J. Torrey and A. Gray, Fl. N. Amer. 1: 211. 1838.
Herbs perennial, acaulous, rhizomes present, fleshy-thickened, densely scaly, stolons absent, bulbs absent. Leaves basal, clustered at rhizome tips; petiole 5–15(–21) cm, sparsely to densely villous, hairs rusty; leaflets 3, green, broadly obcordate, 10–30(–40) mm, lobed 1/5–1/4 length, lobes apically convex, surfaces sparsely villous, oxalate deposits absent. Inflorescences 1-flowered; scapes (6–)11–25 cm, glabrous or sparsely villous. Flowers heterostylous; sepal apices without tubercles; petals white to deep pink, usually with yellow spot sub-basally and prominent purple veins, (8–)15–25 mm. Capsules ovoid, 6–8(–12) mm, glabrate.
Phenology: Flowering Feb–Sep.
Habitat: Douglas fir, mixed fir, cedar-spruce, mixed conifer, and hemlock-maple forests, maple woodlands, alder glens, Gaultheria thickets, stream banks.
Elevation: 10–800(–1000) m.
B.C., Calif., Oreg., Wash.
Oxalis oregana has sometimes been treated as a disjunct geographical taxon of the European O. acetosella Linnaeus (see comments under 21. O. montana).