Family: Rutaceae

Citrus hystrix, commonly known as Kaffir lime or Thai lime, is a small, tropical citrus tree native to Southeast Asia. It is easily recognized by its distinctive bumpy green fruits and uniquely shaped double-lobed leaves, which are glossy and dark green. Both the fruit rind and the aromatic leaves are widely used in Southeast Asian cooking, especially in Thai, Indonesian, and Cambodian dishes, adding a bright, citrusy flavor to curries, soups, and sauces. The tree is also valued for its ornamental appeal, with fragrant flowers and a compact, bushy form that can make it an attractive addition to gardens or potted landscapes.

While Citrus hystrix is not currently considered invasive in Hawai‘i, it does have the potential to naturalize if planted widely, particularly in moist, tropical areas. The tree can spread through seed dispersal by animals, and its vigorous growth in favorable conditions may allow it to compete with native vegetation in some locations. Gardeners should monitor plantings to prevent unintended spread and avoid planting in areas near native forest or sensitive habitats. Overall, Kaffir lime is low-risk when managed responsibly but should be observed for signs of naturalization.

High Risk Traits:

• Grows in tropical climates
  
• Widely naturalized (although region of origin uncertain)
  
• Related Citrus species have become invasive
  
• Branchlets with spines
  
• Host for citrus greening disease
  
• Contact with sap may cause skin irritation
  
• Tolerates many soil types
  
• Self-compatible and spreads by seeds
  
• Fruit possibly consumed by large frugivorous mammals that could disperse the seeds (feral pigs may fill this role in the Hawaiian Islands)

Low Risk Traits:

• Not reported to be invasive or weedy
  
• Edible leaves used in cooking
  
• Not known to spread vegetatively
  
• Relatively large fruits and seeds unlikely to be accidentally dispersed