Family: Asteraceae

Origin, Description & Uses
Mikania micrantha, commonly known as mile-a-minute weed, is a fast-growing tropical vine native to Central and South America. It is recognized for its vigorous climbing habit, heart-shaped leaves, and small clusters of pale white flowers. The plant thrives in warm, humid environments and is capable of rapidly covering trees, shrubs, fences, and other vegetation. In some regions it has been used as a groundcover, for erosion control, and in traditional medicine, but its aggressive growth makes it difficult to manage outside of carefully controlled settings.

Risks & Threats
Although Mikania micrantha is currently not known to be naturalized in the Hawaiian Islands, it possesses traits that are cause for concern and could detrimentally impact tropical island ecosystems if introduced or allowed to spread. This species grows extremely quickly, produces abundant wind-dispersed seeds, and can smother native plants and agricultural crops beneath dense mats of vegetation. In other tropical regions of the world, it has become a serious invasive weed that reduces biodiversity, alters habitats, and increases management costs in forests, farms, and conservation areas. Because of its highly invasive behavior elsewhere, planting or distributing this species is strongly discouraged, and low-risk or native alternatives are recommended for landscaping and groundcover use in Hawaii.

High Risk Traits:

• Broad climate suitability (to 2000 m)
  
• Native & naturalized in tropics/subtropics
  
• Repeated introductions outside native range
  
• Naturalized across multiple continents
  
• Agricultural & forestry weed (smothers crops; high control costs)
  
• Environmental weed (reduces species richness, destroys habitats)
  
• Congeneric weed (M. cordata is noxious)
  
• Allelopathic
  
• Toxic to animals (liver damage)
  
• Tolerates wide soil pH (4.15–8.35) and textures
  
• Climbing/smothering growth habit
  
• Produces viable seed (20,000–40,000 per stalk)
  
• Vegetative reproduction (nodes root easily)
  
• Generates in <1 year; fast growing (8–9 cm/day)
  
• Dispersal: wind, water, machinery, animals, human planting, produce contaminant
  
• Prolific seed production (>1000/m²)
  
• Tolerates fire, cutting, and cultivation

Low Risk Traits:

• No spines, thorns, or burrs
  
• No human toxicity/allergy evidence
  
• No fire hazard
  
• Self-incompatible
  
• Not bird-dispersed
  
• No seed survival through animal guts
  
• Well controlled by herbicides