Oxalis oregana

Sorrel or Oregon Oxalis (Oxalis oregana) is a species of the wood sorrel family, Oxalidaceae, native to moist coastal Douglas-fir and redwood forests of western North America from southwestern British Columbia, Washington, Oregon, and California. This area receives considerable summer moisture from fog drip. It is a short herbaceous perennial plant with erect flowering stems 5-15 centimeter tall. The three leaflets are heart-shaped, 1-4.5 centimeter long with purplish undersides, on 5-20 centimeter stalks. The leaflets prefer to be in shade and will fold up when exposed to sun. The flower cluster is 2.4-4 centimeter in diameter, white to pink with five petals and sepals. The hairy five-chambered seed capsules are egg-shaped, 7-9 millimeter long; seeds are almond shaped. This plant will spread into any area where there is moisture and some shade, but it is fairly easy to control because it is shallowly rooted.