Family: Rafflesiaceae

Origin, Description & Uses
Rafflesia arnoldii is native to the tropical rainforests of southwestern Sumatra and parts of Borneo (including western Sarawak and western Kalimantan). It is one of the most unusual flowering plants in the world, producing the largest known single flower, which can reach up to 1 meter (3 feet) across. Unlike typical plants, it has no visible stems, leaves, or roots of its own and lives as a parasite on grape-vine relatives in the genus Tetrastigma. The flower is famous for its strong odor similar to rotting flesh, which attracts carrion flies that help pollinate it. Outside its native range, it is primarily valued for botanical research, conservation interest, and as a major ecotourism attraction due to its rare and dramatic blooms.

Risks & Threats
This species is not known to be naturalized in Hawaiʻi and is highly unlikely to establish in local ecosystems because it depends entirely on specific host vines that do not occur here. As a highly specialized parasitic plant with very specific habitat requirements, its ability to spread or become invasive is considered extremely low. However, like many rare tropical species, there is always a general concern that intentional introduction or cultivation outside of controlled settings could pose ecological or biosecurity risks. Overall, it is considered a low-risk species for Hawaiʻi, but continued caution is appropriate to ensure it is not introduced in ways that could disrupt native plant communities or protected forest systems.

High Risk Traits:

• Thrives in tropical climates
  
• Parasitic
  
• Reproduces by seeds
  
• Seeds suspected of being dispersed by animals, externally and internally
  
• Limited ecological information may reduce accuracy of risk prediction

Low Risk Traits:

• No reports of invasiveness or naturalization, but no evidence of widespread introduction outside native range
  
• Unarmed (no spines, thorns or burrs)
  
• Ornamental
  
• Dioecious
  
• Not reported to spread vegetatively
  
• Life-cycle, specialized growing and host requirements may limit ability to naturalize