Family: Urticaceae

Origin, Description & Uses
Pilea nummulariifolia (Creeping Charlie) is a fast-growing, trailing herbaceous plant native to Central America, northern South America (including Venezuela and Peru), and the Caribbean. It has small, rounded to slightly crinkled bright green leaves and soft, flexible stems that creep along the ground and root easily at nodes. Because of its dense, cascading growth habit, it is commonly grown as an ornamental groundcover in shaded tropical gardens or as a trailing plant in hanging baskets and containers. It is valued for its lush, carpet-forming appearance in humid, warm environments.

Risks & Threats
In Hawaiʻi, this species is naturalized on Oʻahu and is potentially establishing on Maui and Hawaiʻi Island. While currently considered low risk, its vigorous creeping growth and ability to root wherever stems contact soil allow it to spread locally and form dense mats in moist, shaded areas. This can lead to competition with low-growing native plants or other understory vegetation in suitable habitats. Although it is not currently associated with significant ecological impacts, continued monitoring is recommended to ensure it does not expand beyond cultivated or disturbed areas.

High Risk Traits:

• Native to tropical climates; suited to USDA Zones 10-11
  
• Introduced and naturalized outside native range (e.g., Australia, Florida)
  
• Congeneric weed (Pilea microphylla) is problematic in nurseries
  
• Shade tolerant
  
• Tolerates a wide range of soil pH (mildly acidic to mildly alkaline)
  
• Produces viable seed
  
• Reproduces by vegetative fragmentation (roots at nodes)
  
• Fast-growing; can flower year-round
  
• Intentionally dispersed by people as an ornamental
  
• Tolerates mutilation/cultivation (fragments root readily)

Low Risk Traits:

• Not an environmental weed (no evidence)
  
• No spines, thorns, or burrs
  
• Palatable to grazing animals (e.g., tortoises)
  
• Non-toxic to animals and humans
  
• Not a fire hazard (succulent, moist habitat)
  
• No evidence of persistent seed bank
  
• Likely controllable by herbicides (based on congener)