Family: Proteaceae

Origin, Description & Uses:
Leucadendron argenteum (Cape silvertree) is an evergreen tree native to the southwestern Cape Province of South Africa, where it is naturally restricted to the slopes around Table Mountain. It is best known for its striking silvery-white foliage, which gives the tree a shimmering appearance in sunlight. The species grows as an upright, medium-sized tree and is part of the protea family. It is primarily cultivated as an ornamental plant in gardens and landscapes for its unique foliage texture and color, and it is also occasionally used in cut foliage arrangements.

Risks & Threats:
This species is considered low risk and is not known to be naturalized or invasive in Hawaiʻi. It has no documented history of spreading aggressively in tropical island ecosystems. While it is adapted to nutrient-poor soils and fire-prone environments in its native range, there is currently no evidence that it poses a threat to native habitats in Hawaiʻi. As with any introduced ornamental plant, it is still best to monitor plantings and prefer native or proven low-risk alternatives when possible to support local biodiversity.

High Risk Traits:

• Naturalized in New Zealand (but no evidence in the Hawaiian Islands to date)
  
• Other Leucadendron species are naturalized and may be weedy
  
• Tolerates many soil types as long as they are well-drained
  
• Reproduces by seeds
  
• Can reach maturity in as little as 2 years
  
• Seeds dispersed by wind, possibly by rodents and intentionally by people
  
• Seeds remain in cones on tree for a year or more, and may persist in the soil for 80 years

Low Risk Traits:

• Native to a region with a Mediterranean climate; could limit ability to spread in Hawaiian Islands or other tropical island ecosystems
  
• No reports of negative impacts where naturalized or introduced
  
• Unarmed (no spines, thorns, or burrs)
  
• Non-toxic
  
• Prefers full sun (would limit spread into dense forests)
  
• Dioecious
  
• Not reported to spread vegetatively
  
• Large seeds are wind-dispersed only short distances and are unlikely to be accidentally dispersed
  
• Serotinous seeds remain in tree cones until fire, or hot dry conditions cause them to be released (limits ability to disperse and naturalize)
  
• Killed by fire and disturbance to roots (traits which would minimize invasiveness)