Greenhouse and Nursery - Know your Container Weeds: Oxalis

Oxalis or woodsorrel is a common weed of containers in greenhouses and nurseries. The following is some information and pictures.

Woodsorrel

Of the several species of woodsorrel, probably the two most common are yellow woodsorrel (Oxalis stricta) and creeping woodsorrel (Oxalis corniculata). Both species have very similar weedy growth characteristics:

• Progression from seed to flower in fewer than 3 weeks.
• Production of large amounts of seed.
• Dispersion of seeds up to 12 feet via structures called elators.
• Resembles clover, and leaves are difficult to wet with herbicide solutions due to small, waxy leaves.
  
  Fruits of creeping woodsorrel (Oxalis corniculata L.) showing elators (A) that forcibly expel seeds (B) up to 12 feet.
  
  Both plants are perennial; however, the main difference between the two is that yellow woodsorrel spreads by below-ground rhizomes (stems that creep below the ground), and creeping woodsorrel spreads by stolons (stems that creep above the ground). In addition to being an unsightly weed, this plant has been known to harbor pests such as whiteflies and spider mites.
  
  Flowers and foliage of creeping woodsorrel (Oxalis corniculata L.).
  
  Yellow woodsorrel (Oxalis stricta L).
  
  Information and pictures taken from "Weed Control in Greenhouses" by Mark A. Czarnota, Extension Horticulturist, University of Georgia.