Family: Cupressaceae

Origin, Description & Uses
Leyland cypress is a fast-growing evergreen tree that is a hybrid of Monterey cypress (Hesperocyparis macrocarpa) and Nootka cypress (Callitropsis nootkatensis), originally developed in the United Kingdom. It can reach heights of 15–25 meters (50–80 feet) with a dense, conical form and soft, feathery foliage. This tree is commonly used in landscaping as a privacy screen, windbreak, or ornamental feature due to its rapid growth and ability to form dense hedges. Its attractive green foliage and uniform shape make it a popular choice for both residential and commercial plantings.

Risks, Threats & Management
Leyland cypress is considered low risk in Hawaii. It is not currently known to be invasive and generally does not spread aggressively into natural areas. However, because it grows quickly and can reach large sizes, it may require regular pruning and maintenance to prevent overgrowth in gardens or along property lines. Homeowners planting Leyland cypress are encouraged to manage its growth responsibly and consider site placement to avoid shading or crowding nearby vegetation. For those seeking alternatives, native trees or other low-risk species can provide similar privacy and aesthetic benefits.

High Risk Traits:

• Broad climate suitability (USDA zones 6-10)
  
• Wide soil tolerance (clay, sand, acidic, alkaline)
  
• Tolerates severe pruning
  
• Forms dense hedges/windbreaks
  
• Creates fire hazard
  
• Shade tolerant
  
• Wind-dispersed pollen
  
• Widely introduced by people
  
• Congeneric (C. macrocarpa) is invasive

Low Risk Traits:

• No evidence of naturalization or invasiveness
  
• Sterile hybrid (rarely produces viable seed)
  
• No vegetative fragmentation
  
• No spines, thorns, or burrs
  
• Not toxic to animals or humans
  
• No seed bank
  
• Not suited to tropical/subtropical climates
  
• Resistant to most pests/pathogens