Idaho State Tree: Western White Pine

The Western White Pine is Idaho's official state tree. This evergreen conifer grows 150 to 180 feet tall with trunk diameters of three to eight feet. The largest specimen stands 219 feet high near Elk River, Idaho.

The bark develops dark gray color and cracks into small rectangular segments. Needles grow two to four inches long in bundles of five with blue-green color. Large cylindrical cones measure five to twelve inches long.

The tree grows in mountains across the western United States and Canada. Northern Idaho historically contained the largest western white pine forests.

Common names include Western White Pine, Mountain White Pine, Idaho White Pine, and Silver Pine. The scientific name is Pinus monticola. The species name monticola means 'mountain dweller' in Latin.

The wood earned the nickname 'soft pine' for its straight grain and even texture. Loggers called it 'King Pine' before the 1860s when it dominated moist inland forests.

Idaho adopted the Western White Pine on February 13, 1935. The Ellen Wright Camp, Franklin County Chapter of the Daughters of Pioneers promoted the designation. The law appears in Idaho Statutes Title 67, Chapter 45, Section 67-4504.

The designation came at a pivotal moment. Blister rust had already spread through Idaho forests by 1935. The disease arrived in Vancouver Island around 1910 on imported French ornamental shrubs. By the 1940s, the rust had become epidemic in Idaho.

Legislators chose the white pine for its economic importance. The tree provided Idaho's most valuable timber. The state wanted to honor its forestry heritage even as the species faced catastrophic decline.

White pine blister rust is a fungal disease caused by Cronartium ribicola. The fungus requires two hosts to complete its life cycle: five-needle pines and currant or gooseberry shrubs. Spores travel between hosts on the wind.

The disease entered North America accidentally around 1910. Infected French ornamental shrubs imported to Vancouver Island carried the fungus. The rust spread rapidly through western forests. By the 1940s, it reached epidemic levels in Idaho.

The U.S. Forest Service estimates blister rust killed 90 percent of western white pines west of the Cascades. Today, mature trees exist mostly as scattered individuals. Mountain pine beetles and harvesting compounded the devastation.

Forest geneticists discovered some individual trees showed natural resistance to blister rust. These rare survivors possessed genetic traits that protected them from infection. Scientists collected seeds and pollen from resistant trees.

Breeding efforts began in the 1970s. Researchers tested thousands of trees for rust resistance. They selected the most resistant individuals as parent trees for future generations. This work produced seedlings with inherited disease resistance.

Reforestation using rust-resistant seedlings started in the mid-1970s. The program has planted resistant trees throughout northern Idaho, southern British Columbia, western Montana, and other areas. Progress remains slow because competing species now occupy former white pine habitat.

Idaho's state flower is the Syringa (Philadelphus lewisii), designated in 1931. Also called Lewis' mock orange, the shrub produces fragrant white flowers. The species honors Meriwether Lewis, who collected specimens in Idaho. The flower appeared on Idaho's state seal in 1890.

The needles provide the clearest identification. Five needles grow together in each bundle. Each needle measures two to four inches long with blue-green color. Needles persist three to four years.

The bark starts with red-brown furrows on young trees. Mature trees develop dark gray bark broken into small rectangular blocks. This pattern is unique among North American trees.

Large cones hang from branches. Each cone measures five to twelve inches long with thin, curved scales. Brown when mature, the scales often display spots of white resin.

The Western White Pine symbolizes Idaho's forestry heritage and economic history. Its designation in 1935, amid epidemic disease, shows determination to honor the species despite catastrophe. The ongoing breeding program represents scientific innovation and conservation commitment. The tree's struggle and potential recovery mirror themes of resilience and adaptation.