Family: Araliaceae

Origin, Description & Uses
Hedera helix, commonly known as English ivy, is a climbing evergreen vine native to Europe and Western Asia. It features glossy, dark green leaves that are often lobed and can grow densely over surfaces. English ivy is widely cultivated for ornamental purposes, including ground cover, garden walls, and trellises, due to its fast growth and ability to create lush green coverage. It is also used in erosion control because of its dense, spreading growth habit.

Risks & Threats
English ivy is naturalized on Kaua‘i, Maui, and Hawai‘i Island, and it possesses traits that make it a high-risk species. It grows aggressively, can smother native vegetation, and climbs trees and structures, potentially harming forest health by blocking sunlight and adding weight to branches. Its dense mats can also degrade soil and limit the regeneration of native plants. Because of these impacts on tropical island ecosystems, it is recommended to avoid planting English ivy and instead choose a low-risk or native alternative for landscaping purposes.

High Risk Traits:

• Naturalized on Kauaʻi, Maui, and Hawaiʻi
  
• History of repeated introductions outside native range
  
• Agricultural, forestry, and environmental weed
  
• Congeneric weed (Hedera hibernica and other spp. are invasive)
  
• Allelopathic (may reduce native seed germination)
  
• Toxic to animals and humans; causes allergies
  
• Shade tolerant
  
• Climbing or smothering growth habit
  
• Produces viable seed
  
• Reproduces vegetatively (fragments root easily)
  
• Propagules dispersed intentionally (popular ornamental), by birds, and via animal gut passage

Low Risk Traits:

• Self-incompatible (requires cross-pollination)
  
• Minimum generative time >4 years (often 10+ years)
  
• No wind, external animal, or produce-contaminant dispersal
  
• No persistent seed bank
  
• Well controlled by herbicides
  
• Low tolerance to mutilation, cultivation, or fire
  
• No spines, thorns, or burrs