The majestic western white pine (Pinus Monticola pinaceae) was designated the official state tree of Idaho in 1935. This pine tree grows in the mountains of the western United States and Canada (in the Sierra Nevada, the Cascade Range, the Coast Range, and the northern Rocky Mountains). The tree extends down to sea level in many areas.

Western White Pine is a large tree, regularly growing to 30-50 meters and exceptionally up to 70 meters tall. It is related to Eastern White Pine (Pinus strobus), differing by having larger cones and slightly longer-lasting leaves (needles).

The western white pine is widely grown as an ornamental tree, but has been heavily logged throughout much of its range and also has been seriously affected by white pine blister rust, a fungus that was introduced from Europe in 1909. The U.S. Forest Service has a program for locating and breeding rust-resistant western white pine and sugar pine (seedlings of these trees have been introduced into the wild).

Source:

The State of Idaho - State Symbols: Gov James E. Risch

Links:

State Trees - 50 States List