Oxalis corniculata
Family: 
Oxalidaceae
Life Cycle: 
Perennial
Plant status: 
Weed
Habit: 
Creeping woodsorrel is a low growing, spreading plant. The plant spreads by above ground horizontal stems called stolons. Mature plants form small mounded clumps commonly 4-8 inches high. Foliage is trifoliate, with 3 obcordate (heart-shaped) leaflets. The foliage is pubescent, especially on the margins, and usually green to reddish purple in color.
Flowers: 
Flowers are yellow with 5 petals and 5 stamens and occur in an umbel (cluster). A distinguishable feature of this species is the flower; the petals tend to be separated at the base.
Favorable environments: 
Container
Field
Greenhouse
Favorable environment notes: 
Creeping woodsorrel is widely adaptable and commonly grows in yards, landscape areas, agricultural field areas, greenhouses, nursery grounds and containers. Warm, moist environments, provided by greenhouses and common throughout the spring and summer months in Oregon, are ideal environments for creeping red sorrel to germinate and thrive.
Dissemination: 
Creeping woodsorrel plants produce slightly pubescent, green cylindrical capsules (similar to pods) containing many small (approximately 1/25”) egg shaped, brown seeds. When seeds mature, capsules explode, ejecting seed into the surrounding environment. Seeds of this plant are angled and slightly rough allowing them to adhere onto shoes soles, pots and equipment. This enables the seed to be easily transported around the nursery areas. Another way creeping woodsorrel reproduces, or spreads, is by the stolons it produces. The creeping aboveground horizontal stems root at nodes, forming new plants.
Of interest: 
Creeping woodsorrel is often called creeping redsorrel as well. It is commonly confused with yellow woodsorrel-Oxalis stricta, which also is found in similar growing environments. Both species of Oxalis develop deep taproots, which makes hand-weeding very difficult. During hand weeding, the taproot or stolons can often break off, allowing the plant to re-grow. Pieces of roots and prostrate stems can develop into new plants in favorable conditions often found in nursery settings.
Image by: James Altland, USDA-ARS
Image by: James Altland, USDA-ARS
Image by: James Altland, USDA-ARS
Image by: James Altland, USDA-ARS