Limber pine

Pinus flexilis, the limber pine, is a species of pine tree-the family Pinaceae that occurs in the mountains of the Western United States, Mexico, and Canada. It is also called Rocky Mountain white pine. A limber pine in Eagle Cap Wilderness, Oregon has been documented as over 2000 years old, and another one was confirmed at 1140 years old. Another candidate for the oldest limber pine was identified in 2006 near the Alta Ski Area in Utah; called 'Twister', the tree was confirmed to be at least 1700 years old and thought to be even older. The largest part of the limber pine's range is in the Rocky Mountains, from southwest Alberta and southeastern British Columbia south through Colorado and New Mexico into the northern states of Mexico. It is also found through the Great Basin states of Nevada and Utah, in the eastern Sierra Nevada and White Mountains of Northern California, and in the San Bernardino and San Gabriel Mountains of the Transverse Ranges in Southern California. Continuing south the species is found in the San Jacinto Mountains, Santa Rosa Mountains, and Hot Springs Mountain of the Peninsular Ranges. There are small disjunct populations in eastern Washington and Oregon, in western North Dakota and Nebraska, and in the Black Hills of South Dakota. It is found at a wide range of altitudes depending on the latitude, from 850 to 3,810 metres (2,790 to 12,500 ft). In the northern half of its range, it grows in the montane zone near the lower tree line; in the middle of its range between the 45th and 40th parallels, it grows on windswept sites in the montane and subalpine zones; and in the southern part of its range, it grows mainly at high elevations in the subalpine zone near the upper tree line. Its pliant branches gives it the common name 'limber' and specific epithet flexilis. Its long needles are a dark, blueish green, its bark is heavily creased and dark grey. Its pale wood is lightweight and soft. Pinus flexilis is typically a high-elevation pine, often marking the tree line either on its own, or with whitebark pine (Pinus albicaulis), either of the bristlecone pines, or lodgepole pine (Pinus contorta). In favourable conditions, it makes a tree to 20 meters (65 ft), rarely 25 meters (80 ft) tall. However, on exposed treeline sites, mature trees are much smaller, reaching heights of only 5–10 meters (15–35 ft). In steeply-sloping, rocky, and windswept terrain in the Rocky Mountains of southern Alberta, limber pine is even more stunted, occurring in old stands where mature trees are consistently less than 3 metres (10 ft) in height.