Family: Phytolaccaeae

Origin, Description & Uses
Phytolacca dioica, commonly known as ombú, is a large, fast-growing tree native to parts of South America, including Bolivia, Brazil, and northern Argentina. Despite its massive size and broad canopy, ombú is technically a giant herbaceous plant with a thick, water-storing trunk and soft wood. It is widely planted in tropical and subtropical regions as a shade tree, ornamental specimen, and windbreak due to its dramatic appearance, drought tolerance, and rapid growth. Ombú produces dense foliage and clusters of berries that can be spread by birds and other animals.

Risks & Threats
Ombú is naturalized on Hawaiʻi Island and is considered potentially naturalizing on Oʻahu. This species possesses traits that are cause for concern, including rapid growth, prolific seed production, and the ability to spread into disturbed and unmanaged areas. Its large canopy can shade out native vegetation and alter habitat structure, while its vigorous growth may allow it to outcompete desirable plants in tropical island ecosystems. Because ombú has the potential to detrimentally impact Hawaiʻi’s unique environments, planting should be approached with caution. When suitable, choose a low-risk or native alternative to help protect island ecosystems and reduce the spread of invasive species.

High Risk Traits:

• Naturalized outside native range (Mediterranean, Hawaii, South Africa)
  
• Garden/amenity/disturbance weed; aggressive root suckers
  
• Environmental weed (Category 3 invader in South Africa; problem in California)
  
• Congeneric weeds (other Phytolacca species are serious weeds)
  
• Unpalatable to grazing animals (poisonous sap)
  
• Toxic to animals (fruits toxic to livestock; cattle/chicken poisoning)
  
• Broad climate suitability (USDA zones 9b–11; tolerates light frost)
  
• Tolerates wide range of soil types
  
• Produces viable seed
  
• Bird-dispersed seeds
  
• Seeds survive gut passage
  
• Prolific seed production (~150,000 seeds/kg)

Low Risk Traits:

• No spines, thorns, or burrs
  
• No significant pest/pathogen host
  
• Low human toxicity/allergenicity (rare case only)
  
• Fire resistant (water-storing trunk)
  
• Not shade tolerant
  
• Dioecious (reduces self-fertilization)
  
• Not wind-dispersed or water-dispersed
  
• No vegetative spread