Pinus flexilis, the limber pine, is a species of pine tree in 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 2,000 years old, and another one was confirmed at 1,140 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 1,700 years old and thought to be even older.

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