Family: Ochnaceae

Origin, Description & Uses
Ochna thomasiana (Mickey Mouse bush) is native to southern Somalia through eastern Tanzania, including Zanzibar and Pemba. It is an ornamental shrub or small tree widely planted for its attractive glossy green leaves, bright yellow flowers, and distinctive fruits that develop black seeds with red sepals resembling “Mickey Mouse” ears. Because of its showy appearance and relatively compact growth habit, it has been used in tropical and subtropical landscaping, hedges, and garden borders.

Risks & Threats
In Hawaiʻi, Mickey Mouse bush is already naturalized on Kauaʻi, Oʻahu, Maui, and Molokaʻi, and is potentially naturalizing on Lānaʻi and Hawaiʻi Island. It produces seeds that can be readily spread by birds and other wildlife, allowing it to establish beyond planted areas. Once established, it may form dense stands and compete with native vegetation, especially in disturbed or open habitats. As a naturalized species with traits that are cause for concern, it could detrimentally impact tropical island ecosystems by contributing to habitat degradation and biodiversity loss. Care should be taken to avoid further spread, and low-risk or native alternatives are recommended when suitable options are available.

High Risk Traits:

• High climate suitability for tropical/subtropical regions (score 2)
  
• Naturalized beyond native range (Hawaii, French Polynesia)
  
• Weedy in gardens, disturbed mesic forests, and amenity areas
  
• Congeneric weed (Ochna serrulata is a significant environmental weed in Australia and Hawaii)
  
• Shade tolerant (grows as understory shrub in disturbed mesic forests)
  
• Produces viable seed (seedlings observed near parent plants)
  
• Vegetative reproduction possible (via cuttings)
  
• Bird dispersed (fleshy drupelets attractive to frugivorous birds)
  
• Seeds survive gut passage (enhances dispersal)
  
• Intentional dispersal by people (horticultural trade)

Low Risk Traits:

• No spines, thorns, or burrs
  
• No evidence of toxicity to humans or animals
  
• Not a major host for recognized pests/pathogens
  
• Limited soil tolerance (narrow pH range: 5.6–7.5)
  
• No prolific seed production (seeds are large, fewer per plant)
  
• Not wind-dispersed (large seeds)
  
• No external animal dispersal (no hooks/barbs)