Family: Euphorbiaceae

Origin, Description & Uses
Florida hammock sandmat (Euphorbia ophthalmica) is a small, low-growing annual herb native to the southeastern United States, Central America, the Caribbean, and much of tropical and subtropical South America. It forms spreading mats of slender stems with tiny opposite leaves and produces inconspicuous flowers typical of spurges, followed by small seed capsules. This species commonly grows in lawns, gardens, nurseries, cultivated fields, roadsides, and other disturbed areas. Although it has no major ornamental or agricultural value, it is occasionally moved inadvertently through the nursery trade and in contaminated soil associated with potted plants.

Risks & Threats
Florida hammock sandmat is naturalized on Oʻahu and is potentially naturalizing on Kauaʻi, Lānaʻi, Maui, and Hawaiʻi Island. It possesses several traits associated with invasive plants, including prolific seed production, rapid establishment in disturbed habitats, and the ability to spread through human activities such as the movement of nursery stock and soil. These characteristics are cause for concern because they could enable the species to expand into additional areas and negatively impact tropical island ecosystems by competing with native vegetation and increasing weed pressure in managed and natural habitats. Where possible, choose a low-risk or native alternative instead of planting or transporting this species. Because it is already established on Oʻahu, efforts should focus on preventing its introduction and spread into areas where it is not yet widely established, helping to minimize further ecological impacts.

High Risk Traits:

• Invasive: Naturalized in Australia, Hawaii, Galápagos, and multiple U.S. states
  
• Hawaiian Islands status: Naturalized on Oʻahu; potentially naturalizing on Kauaʻi, Lānaʻi, Maui, and Hawaiʻi Island
  
• Disturbance weed: Thrives in gardens, roadsides, nurseries, and flowerbeds
  
• Nursery contaminant: Spreads via contaminated potting soil and stock
  
• Climate versatility: Grows in temperate to tropical regions (USDA 8a to tropics); 0–3,657 m elevation
  
• Fast generation: Annual; reaches maturity in < 1 year
  
• High seed output: Prolific seeder (> 1,000 seeds/m² likely)
  
• Self-compatible: Capable of self-pollination
  
• Generalist pollination: No specialist pollinators required
  
• Toxic: Milky sap irritates skin and is poisonous if ingested (humans and animals)
  
• Disturbance-adapted: Benefits from fire, cultivation, and soil disturbance
  
• Unintentional dispersal: Readily moved by vehicles, footwear, and contaminated soil

Low Risk Traits:

• No fire hazard: Small, low-biomass annual
  
• No shade tolerance: Requires full sun
  
• Not aquatic: Strictly terrestrial
  
• No vegetative spread: No natural fragmentation (stems root only artificially)
  
• No climbing: Prostrate, non-smothering
  
• No specialized dispersal: Lacks adaptations for wind, water, or animal transport
  
• Short-lived seed bank: Seeds viable < 1 year
  
• Herbicide susceptibility: Controlled by pre- and early post-emergence herbicides