Family: Casuarinaceae

Casuarina cunninghamiana, commonly known as cunninghamia beefwood or river sheoak, is a fast-growing, evergreen tree native to eastern and northern Australia, and New Guinea, where it typically grows along freshwater rivers and streams. This tree is characterized by its slender, drooping branchlets that resemble pine needles and small, cone-like fruit. Valued for its hardy nature, it has been introduced around the world for use in windbreaks, erosion control along waterways, and as a source of firewood and timber.

While useful in forestry, Casuarina cunninghamiana poses significant ecological risks in non-native regions like Florida, USA, where it has become a problematic invasive species. It is classified as an environmental weed because its prolific, wind- and water-dispersed seeds allow it to spread rapidly along riverbanks, outcompeting native vegetation. As a nitrogen-fixing tree, it can alter soil chemistry, and it may hybridize with other invasive casuarina species. These traits enable it to form dense stands that disrupt local ecosystems, increase fire risk, and are difficult to control once established.

High Risk Traits:

• Naturalized outside native range
  
• Environmental weed (e.g., Florida)
  
• Related species are invasive
  
• Hosts pests/pathogens
  
• Increases fire risk
  
• Tolerates varied soils
  
• Nitrogen-fixing
  
• High seed production
  
• Resprouts after damage
  
• Hybridizes naturally
  
• Early maturity (under 3 years)
  
• Wind- and water-dispersed seeds

Low Risk Traits:

• Not a crop or garden weed
  
• No thorns, toxins, or allelopathy
  
• Not shade tolerant
  
• Not self-fertile
  
• No vegetative spread in nature
  
• Not dispersed by animals or contamination
  
• No persistent seed bank