aka Oregon Oxalis, Oregon Wood-sorrel, Wood Sorrel. A luxuriant ground cover of attractive “shamrock” leaves sends up flower stems to 6″ (15 cm) tall with one flower per stem (the less common O. trilliifolia has 6 – 8 flowers). The funnel-shaped flowers have five petals, each 1/2″ – 3/4″ in length, with distinctive purple veins. Leaf stems are a little longer (to 8″) and support numerous clover-like leaves with three heart-shaped and folded leaflets. Common in shady moist woods to 2,500′ elevation.