Family: Pinaceae

Origin, Description & Uses
Pseudotsuga menziesii (Douglas fir) is a large evergreen conifer native to western North America, ranging from southeastern Alaska south through the western United States to Mexico. It is valued worldwide as an important timber tree and is widely planted for lumber production, windbreaks, reforestation, and ornamental landscaping. Douglas fir is known for its tall, straight trunk, soft needles, and distinctive cones with three-pointed bracts. It is also commonly grown as a Christmas tree and is appreciated for its adaptability and rapid growth in suitable climates.

Risks & Threats
Although Douglas fir is not known to be naturalized in Hawaii, it does possess traits that are cause for concern. In other regions, it has shown the ability to establish outside cultivation, especially in cool, moist environments. Its fast growth, long lifespan, and ability to produce abundant seed may allow it to spread under favorable conditions. Dense stands can also alter native plant communities and ecosystem processes. Caution is recommended to ensure that it will not negatively impact Hawaii.

High Risk Traits:

• Naturalized in multiple countries (NZ, Europe, S. America)
  
• Environmental weed in shrublands, grasslands, & forests
  
• Broad climate & soil tolerance
  
• Widely introduced for forestry
  
• Forms dense thickets / pure stands
  
• Shade-tolerant at seedling stage
  
• Creates fire hazard in non-native ecosystems
  
• Produces viable seed
  
• Self-compatible
  
• Wind-dispersed seeds
  
• Intentionally spread by people
  
• Animal-dispersed (squirrels, mice, birds)
  
• Persistent seed bank (1–2 years)
  
• Tolerates fire, mutilation, & cultivation

Low Risk Traits:

• No spines, thorns, or burrs
  
• Non-toxic to humans & animals
  
• No vegetative reproduction
  
• Not a garden, agricultural, or congeneric weed