Family: Aquifoliaceae

Origin, Description & Uses
Ilex cassine, commonly known as dahoon holly, is a small to medium-sized evergreen tree native to the southeastern United States, the Caribbean, and parts of Central America. It naturally occurs in wetlands, swamps, and along streambanks, where it thrives in moist to flooded soils. The tree has glossy, dark green leaves and produces clusters of bright red berries that persist into winter and attract birds. Dahoon holly is sometimes used as an ornamental plant in landscaping for its attractive foliage and fruit, and it can function as a hedge, screen, or wildlife-friendly planting in suitable environments.

Risks & Threats
In Hawaiʻi, dahoon holly is naturalized on Oʻahu and Hawaiʻi Island and is considered a high-risk species. It possesses traits that are cause for concern, such as prolific berry production, bird-mediated seed dispersal, and the ability to establish in wet natural habitats. These characteristics enable it to spread beyond cultivation and potentially invade native ecosystems, where it may outcompete native plants and alter habitat structure. Because it could detrimentally impact tropical island ecosystems, it is recommended to avoid planting this species and instead choose a low-risk or native alternative if intentionally cultivated.

High Risk Traits:

• Broad climate suitability
  
• Grows in regions with tropical climates
  
• Naturalized on Oahu, and Hawaii (Hawaiian Islands)
  
• Other Ilex species are invasive
  
• May be slightly toxic
  
• Shade tolerant (could potentially spread into intact forests)
  
• Tolerates many soil types
  
• Reproduces by seeds, and possibly clonally
  
• Hybridizes with other Ilex species
  
• Seeds dispersed by birds, water and intentionally by people
  
• Seeds my remain viable in soil for two years
  
• Able to resprout after cutting and pruning

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Palatable to livestock (but palatability is reported to be low)
  
• Valued as an ornamental tree
  
• Dioecious, requiring male and female trees for reproduction
  
• Reaches maturity in 4+ years