Family: Pinaceae

Origin, Description & Uses
Pinus jeffreyi (Jeffrey pine) is a large evergreen conifer native to the mountains of southern Oregon, California, and northern Baja California, Mexico. It is closely related to ponderosa pine and is valued for its tall, straight trunk, long bluish-green needles, and large woody cones. In its native range, Jeffrey pine grows in dry montane forests and is well adapted to cool climates, seasonal drought, and fire-prone environments. It has been planted as an ornamental and forestry tree for timber, windbreaks, reforestation, and landscape use in suitable temperate regions. In Hawaii, it has become naturalized in parts of West Maui and Haleakalā National Park on Maui.

Risks & Threats
Although Jeffrey pine is not currently considered among Hawaii’s most damaging invasive trees, it is naturalized and possesses traits that are cause for concern. Pines can spread by seed into open or disturbed habitats, forming dense stands that may alter native plant communities, increase competition for water and nutrients, and change fire behavior by adding flammable needle litter and woody fuels. In sensitive high-elevation ecosystems, the establishment of non-native conifers may gradually alter habitat structure and ecosystem processes. Ongoing evaluation is needed to better understand the long-term impacts of Pinus jeffreyi in Hawaii, and caution is recommended when planting this species to help ensure that it will not negatively impact native ecosystems.

High Risk Traits:

• Elevation range exceeds 2000 m, demonstrating environmental versatility
  
• Naturalizing on West Maui and Haleakala National Park, Maui (Hawaiian Islands) and reported to be naturalized in Spain
  
• Other Pinus species are invasive
  
• Potentially toxic to cattle
  
• Pollen may be allergenic
  
• Increases fire risk in natural ecosystems
  
• Forms relatively pure stands in native range
  
• Reproduces by seeds
  
• Hybridizes with ponderosa pine (P. ponderosa) and Coulter pine (P. coulteri)
  
• Seeds dispersed by wind, seed caching animals and intentionally by people
  
• Potential for prolific seed production during mast years (every 2 to 4 years)
  
• Tolerates fire

Low Risk Traits:

• No reports of invasiveness or negative impacts where introduced
  
• Unarmed (no spines, thorns, or burrs)
  
• Palatable to browsing and grazing animals
  
• Shade-intolerant
  
• Not reported to spread vegetatively
  
• Long time to reproductive maturity (>8 years)