Family: Apocynaceae

Origin, Description & Uses:
Hoya australis (Samoan wax flower) is a tropical climbing vine native to Australia, Papua New Guinea, and parts of Indonesia. It is well known for its thick, waxy leaves and clusters of fragrant, star-shaped white flowers that produce a sweet scent, especially in the evening. This attractive growth habit has made it a popular ornamental plant for hanging baskets, trellises, and indoor houseplant collections in warm climates and greenhouses. It is valued for its drought tolerance, low maintenance needs, and long-lasting decorative flowers.

Risks & Threats:
This species is naturalized in Hawaiʻi and possesses traits that are cause for concern, including vigorous vining growth, adaptability to a range of light conditions, and the ability to spread in warm, humid environments. In suitable habitats, it may climb over and smother native vegetation or alter plant community structure, particularly in disturbed tropical lowland ecosystems. While often cultivated for ornamental use, its persistence outside of gardens raises ecological concerns. Because it could detrimentally impact tropical island ecosystems if it spreads further, it is recommended to choose a low-risk or native alternative when selecting plants for intentional cultivation in Hawaiʻi.

High Risk Traits:

• Naturalized in Hawaii (Maui)
  
• Native to tropical/subtropical climates
  
• Widely cultivated outside native range
  
• Unpalatable to grazing animals
  
• Toxic to animals (cattle, sheep)
  
• Toxic to humans if ingested
  
• Shade tolerant
  
• Climbing, smothering growth habit
  
• Produces viable seed
  
• Wind-dispersed seeds
  
• Intentionally spread by people (ornamental)

Low Risk Traits:

• No spines, thorns, or burrs
  
• No agricultural/weed impacts documented
  
• Requires specialist pollinators
  
• No vegetative fragmentation spread
  
• Slow to flower (~4 years)
  
• No persistent seed bank (seed doesn't store well)
  
• No fire hazard (succulent)