Family: Fabaceae

Origin, Description & Uses:
Erythrina subumbrans, commonly known as the December tree, is a fast-growing, deciduous tree native to tropical regions of South and Southeast Asia. It is valued for its striking seasonal display of bright red to orange flowers that typically bloom in the cooler months when the tree is leafless. This species has a broad, spreading canopy and is often planted as an ornamental or shade tree in tropical landscapes. It is also used in agroforestry systems, where it can serve as a living fence, support for crops like pepper or vanilla, and a nitrogen-fixing tree that helps improve soil fertility.

Risks & Threats:
Although Erythrina subumbrans is not currently known to be naturalized in Hawaiʻi, it does possess traits that raise concern. Like other Erythrina species, it can grow rapidly, reproduce by seed and cuttings, and thrive in a variety of environmental conditions. These characteristics increase its potential to spread beyond cultivation. There is also concern that it could compete with native vegetation or alter soil conditions in sensitive ecosystems. Because of these risk factors, further evaluation is needed to determine its potential to establish and impact Hawaiʻi’s ecosystems.

High Risk Traits:

• Produces thorns on young branches
  
• Congeneric weed
  
• Rapidly regenerates after coppicing or pollarding
  
• Nitrogen-fixing, can thrive in poor soils
  
• Hybridizes naturally with other Erythrina species
  
• Bird-pollinated, may lack pollinators outside native range
  
• Intentionally dispersed by people as an ornamental
  
• Dispersed by water and birds
  
• Seeds survive gut passage
  
• Broad climate suitability (wide altitude and latitude range)

Low Risk Traits:

• Palatable as fodder (not unpalatable)
  
• Non-toxic to animals and humans (leaves are eaten)
  
• No fire hazard (occurs in moist areas)
  
• Narrow soil tolerance (prefers light, acidic, free-draining soils)
  
• No evidence of naturalization or weediness
  
• No vegetative spread in the wild
  
• Large seeds with no attachment structures, limiting unintentional dispersal
  
• Low seed production (1–5 seeds per pod)
  
• Self-incompatible, requiring cross-pollination