Family: Altingiaceae

Origin, Description & Uses: Liquidambar styraciflua, commonly known as sweetgum, American storax, or redgum, is a large deciduous tree native to the eastern and central United States, Mexico, and parts of Central America. It is valued for its tall, symmetrical shape, star-shaped leaves, and striking fall colors that range from yellow and orange to deep red and purple. The tree also produces distinctive spiky seed balls and fragrant resin historically used in traditional medicines, perfumes, and chewing gum. Sweetgum is widely planted as an ornamental shade tree in parks, streetscapes, and large landscapes, and its hardwood is used for furniture, veneer, flooring, and other wood products.

Risks & Threats: Although Liquidambar styraciflua is not currently known to be naturalized in the Hawaiian Islands, it possesses several traits that raise concerns for tropical island ecosystems. This species produces abundant seeds that can be spread by wind and water, and it is adaptable to a wide range of soil and climate conditions. In suitable environments, sweetgum can form dense stands that may compete with native vegetation for sunlight, water, and space. Its ability to establish in disturbed areas increases the risk of spread into sensitive habitats if introduced more widely. Because invasive trees can alter ecosystem structure and reduce native biodiversity, planting caution is advised. When possible, choose low risk or native alternatives better suited to Hawaiʻi’s unique environments.

High Risk Traits:

• Elevation range exceeds 1000 m and broad climate suitability, demonstrating environmental versatility
  
• Grows in tropical climates
  
• Naturalized in New Zealand, and possibly elsewhere outside native range (but no evidence in Hawaiian Islands to date)
  
• A fast-growing pioneer tree that can become a nuisance in landscaping due to the spikey fruiting capsules, aggressive roots and potential to form dense stands
  
• A possible forestry weed
  
• Spiny fruiting capsules can be a landscaping hazard
  
• Tolerates many soil types
  
• Forms pure stands in native range
  
• Reproduces by seeds and vegetatively by root suckers
  
• Seeds dispersed by wind, secondarily by water and intentionally by people
  
• Orthodox seeds may form a seed bank that persists for one or more years
  
• Able to coppice and resprout after cutting and fire

Low Risk Traits:

• Provides fodder for livestock
  
• Mostly shade intolerant (could limit spread into intact forests)
  
• Self-incompatible
  
• Long time to reproductive maturity (20-30 years typical, although some trees could reach maturity in 4-5 years)
  
• Herbicides may provide effective control