The Trillium-leaved Woodsorrel (Oxalis trilliifolia Hook.) is one of three endemic woodsorrels found in the Pacific Northwest. It naturally occurs west of the Cascade Crest in Washington, Oregon, and California. There are a few outlying populations in Eastern Oregon.
It is an early summer blooming perennial that typically grows to 5 to 10 inches in height.
The five-petaled white to pinkish flowers are streaked with reddish veins. The flowers are 0.5 inch long. The plants can form verdant dense carpets in dense conifer forests. The 1.5 inch long leaves are typical of woodsorrels with three leaflets borne on the end of 2 to 8 inch long petioles. Each leaflet are heart-shaped with a fold in the middle.
It can make a fine ground cover with enough moisture.