7. Bristlecone Pines
Bristlecone pines are among Earth’s oldest living organisms, with some individuals exceeding 5,000 years in age. (britannica.com) These ancient trees thrive in harsh environments, often at elevations between 6,500 and 11,000 feet, where they face extreme cold, dry soils, high winds, and short growing seasons. (nps.gov) Their longevity is attributed to several factors: slow growth rates, dense and resinous wood that resists decay and pests, and the ability to survive partial die-back while maintaining vital functions. (fs.usda.gov)