Family: Oleaceae

Origin, Description & Uses
Olea europaea subsp. africana, commonly known as wild olive or African olive, is a hardy evergreen tree native to parts of Africa where it grows in dry woodlands, rocky slopes, and open savannas. It is closely related to the cultivated olive and has similar small, leathery leaves with a gray-green underside, along with small, dark fruits that resemble miniature olives. In landscaping, it is valued for its toughness, drought tolerance, and ability to thrive in poor soils, making it a popular choice for hedges, windbreaks, and ornamental plantings in warm climates.

Risks & Threats
This species is naturalized in Hawaiʻi on Kauaʻi, Oʻahu, Lānaʻi, Maui, and Hawaiʻi Island, and it has traits that are cause for concern. Its fruits are readily dispersed by birds, allowing it to spread into natural areas where it can establish dense stands and outcompete native vegetation. Its drought tolerance and ability to thrive in a wide range of conditions increase its potential to invade dry and mesic ecosystems, where it may alter habitat structure and reduce biodiversity. Because it is naturalized and capable of spreading beyond cultivation, it could detrimentally impact tropical island ecosystems. When possible, choosing a low-risk or native alternative is strongly recommended to help protect Hawaiʻi’s unique environments.

High Risk Traits:

• Broad climate tolerance (tropical to warm temperate)
  
• Naturalized in Hawaii, Australia, New Zealand
  
• Forms dense, shading thickets
  
• Shade tolerant
  
• Tolerates poor, shallow, acidic to neutral soils
  
• Produces abundant viable seed (up to 425,000/tree)
  
• Seedling mats >1,200/m²
  
• Soil seed bank persists ~2.4 years
  
• Bird-dispersed
  
• Seeds survive bird guts (germination enhanced)
  
• Resprouts from lignotuber, root suckers, and coppice
  
• Tolerates fire, cutting, and grazing
  
• Already invasive in multiple regions

Low Risk Traits:

• Matures in 5–6 years
  
• No spines, thorns, or burrs
  
• No evidence of allelopathy or toxicity
  
• No vegetative fragmentation
  
• No external animal or produce contamination dispersal
  
• Controlled by herbicides (e.g., cut-stump)
  
• Seed bank short (~2.4 years), allowing management window