Family: Euphorbiaceae

Origin, Description & Uses:
Euphorbia prostrata, commonly known as prostrate sandmat or prostrate spurge, is a low-growing, mat-forming plant native to tropical and subtropical regions of the Americas. It typically grows flat along the ground, with slender stems, small oval leaves, and tiny clustered flowers. This species thrives in disturbed areas such as lawns, roadsides, sidewalks, and agricultural fields, where it can tolerate compacted soils and dry conditions. While not widely cultivated for ornamental purposes, it has been used in traditional medicine in some regions for minor ailments, and is sometimes noted for its ability to quickly cover bare ground.

Risks & Threats:
Euphorbia prostrata is naturalized across the Hawaiian Islands, including Midway Atoll (Kuaihelani), Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and Hawaiʻi Island. It possesses traits that are cause for concern, including rapid growth, prolific seed production, and the ability to thrive in a wide range of environmental conditions. These characteristics allow it to spread easily and outcompete native vegetation, particularly in disturbed or open habitats. Its presence can contribute to reduced biodiversity and altered ecosystem dynamics. Because it is already established and spreading, this species could detrimentally impact tropical island ecosystems, and its management can be challenging once populations become widespread.

High Risk Traits:

• Elevation range exceeds 2000 m, demonstrating environmental versatility
  
• Thrives in tropical climates
  
• Naturalized on all the main Hawaiian Islands and widely naturalized elsewhere
  
• Disturbance-adapted lawn and crop weed
  
• Other Euphorbia species are invasive weeds
  
• Allelopathic
  
• Toxic to livestock
  
• Tolerates many soil types
  
• Reproduces by prolific seed production
  
• Annual, reaching maturity in one growing season
  
• Seeds dispersed by wind, water, vehicles, in soil and in contaminated agricultural produce
  
• Seeds survive gut passage
  
• Able to resprout from roots and tolerates mowing

Low Risk Traits:

• In Hawaiian Islands, occurs in low elevation, dry disturbed sites and generally not considered a significant environmental weed
  
• Unarmed (no spines, thorns, or burrs)
  
• Palatable to animals despite reports of toxicity
  
• Not reported to spread vegetatively
  
• Herbicides may provide effective control