Family: Oxalidaceae

Origin, Description & Uses
Oxalis stricta (upright yellow sorrel, yellow sheep sorrel, yellow wood sorrel) is a small herbaceous plant native to temperate regions of Central and Eastern China, northern and central Japan, and parts of North America. It typically grows as a low, clumping or spreading annual or short-lived perennial with delicate trifoliate leaves resembling clover and small, bright yellow flowers. The plant is commonly found in gardens, lawns, agricultural fields, roadsides, and disturbed soils. In some regions it has been used in traditional contexts as a minor edible plant, with leaves and stems sometimes consumed in small amounts for their tangy, lemon-like flavor, though it contains oxalic acid and should be eaten sparingly.

Risks & Threats
Although Oxalis stricta is currently not known to be naturalized in the Hawaiian Islands, it possesses traits that raise concern for tropical island ecosystems. It produces abundant seeds that are easily dispersed and can persist in soil seed banks, allowing it to spread rapidly in suitable conditions. Its ability to thrive in disturbed habitats, including lawns, gardens, and agricultural areas, increases the risk of establishment and potential competition with native groundcover species. Once established, it can form dense patches that may be difficult to manage and can contribute to displacement of low-growing native plants. Given these characteristics, it is recommended to choose low-risk or native alternatives whenever possible to help protect Hawaii’s ecosystems.

High Risk Traits:

• Broad climate suitability, and elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Naturalized outside native range, but not reported in the Hawaiian Islands to date
  
• A weed of lawns, gardens, greenhouses and crops
  
• Other Oxalis species are invasive
  
• Contains oxalate that can be toxic to animals if consumed in large quantities
  
• Host of crop pests and pathogens
  
• Shade tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds and vegetatively by rhizomes
  
• Hybridizes with other Oxalis species
  
• Autogamous and self-compatible
  
• Reaches maturity rapidly (<1 year)
  
• Seeds dispersed ballistically, as a contaminant, internally by animals, and likely through external attachment to machines, equipment and animals
  
• Prolific seed production
  
• Forms a persistent seed bank
  
• Tolerates mowing

Low Risk Traits:

• A temperate climate weed; would likely only impact tropical island ecosystems at higher elevations
  
• Unarmed (no spines, thorns, or burrs)
  
• Browsed by deer and other animals (palatable despite potential toxicity)
  
• Herbicides may provide effective control