Family: Euphorbiaceae

Origin, Description & Uses
Jatropha curcas, commonly known as physic nut, is a small tree or large shrub native to tropical regions of the Americas but now widely distributed across the tropics. It typically grows 6–10 meters tall, with smooth gray bark, large lobed leaves, and clusters of small yellow-green flowers that develop into capsule-like fruits containing oil-rich seeds. Physic nut has been widely cultivated for its many uses, including as a living fence, ornamental plant, and for erosion control. Its seeds are especially valued for producing biofuel oil, and the plant has also been used in traditional medicine, though all parts of the plant are toxic if ingested.

Risks & Threats
In Hawaiʻi, physic nut is naturalized on Maui and Hawaiʻi Island and is potentially naturalizing on Oʻahu. This species possesses traits that are cause for concern, including rapid growth, drought tolerance, and the ability to spread by seed into disturbed and dry habitats. It can form dense stands that outcompete native vegetation and alter ecosystem structure. Because it is toxic, it may also pose risks to people, pets, and livestock. As a high-risk species, it has the potential to detrimentally impact tropical island ecosystems if its spread continues. For these reasons, it is recommended to avoid planting physic nut and instead choose low-risk or native alternatives for landscaping and agricultural use.

High Risk Traits:

• Naturalized pantropically; a weed in many countries
  
• Declared noxious (environmental weed) in Western Australia
  
• Congeneric weeds exist
  
• Unpalatable to grazing animals
  
• Toxic to livestock and humans (seeds contain curcin)
  
• Forms dense thickets
  
• Tolerates poor, sandy, gravelly, and saline soils
  
• Self-compatible (can self-pollinate)
  
• Reaches reproductive age within 2 years
  
• Dispersed unintentionally (mud on vehicles, animals)
  
• Dispersed intentionally (cultivated for oil, medicine, hedges)
  
• Dispersed by water
  
• Tolerates mutilation/pruning

Low Risk Traits:

• No spines, thorns, or burrs
  
• Not an agricultural/forestry weed
  
• No major pest/pathogen host
  
• Not shade tolerant
  
• Not wind-, bird-, or animal-externally dispersed
  
• No seed survival through gut (toxic)
  
• Not prolific seed producer
  
• Controllable with herbicides