Return to Native Trees of the Southern Rocky Mountains

The Bristlecone pine is a usually a small tree, renowned for growing to great age on rocky soil in harsh conditions. Bristlecone also grows to large size in forest settings, and even grows in meadows on occasion. It is found from 7000 feet above sea level to treeline. It can survive on rocky windy ridge-tops. It is also found mixed with Limber pine in woods up to several hundred acres, or with other trees typical at the elevation. Bristlecone and Limber pine can survive where winter winds sweep the high country free of snow, while the neighboring spruce and fir are buried several feet deep.

This tree is very long-lived. It can grow in cool places with very little water, where it grows so slowly that the growth rings are microscopic - as many as 1100 in five inches. It may be prostrate near treeline, or reach 40 feet high in a protected forest.

In harsh conditions a Bristlecone five feet high may be over 500 years old. It may grow an inch a century once it is mature. Bristlecone pines near South Park are the oldest trees in Colorado. The oldest Colorado Bristlecone pine is at least 2436 years old. It grows in southern Park County near Guffey in an area closed to the public. A Bristlecone pine ( Pinus longavea ) in California is about 4600 years old, probably the oldest individual tree on earth.

The Limber pine - Bristlecone pine combination can move into an area after fire removes other trees. Once established, these stands may on occasion be invaded by Douglas fir, Aspen, Engelmann spruce, or Subalpine fir, since protection from the wind is provided. A climax forest of another species may be established. In many cases small permanent groves of Bristlecone and Limber pine persist.

Bristlecone pine is found south of Berthoud Pass and James Peak in Colorado; never north of the fortieth parallel. Groves of Bristlecone pine are found above Manitou on Pikes Peak, and larger groves in the San Juan Forest. It is widespread around South Park. Notable groves that can be reached by car are found northwest of Alma, and on Mt. Evans. Woods of Limber pine mixed with Bristlecone are even more widely found, but Bristlecone pine is not a common tree in Colorado, or anywhere in its range, which extends on mountains west to California and south into New Mexico.

The scientific name is Pinus aristata , from arista , a "beard", referring to the bristles on the cones. The California tree is of variety longea , meaning long-lived. It lacks the resin drops on the needles.

Identifying features of Bristlecone Pine

Bristlecone and Limber pine may be confused. Bristlecone has softer, thinner, needles, 1 1/2 inches long or less, with white resin specks. The Bristlecone cones are smaller and darker than Limber pine cones, and have bristles on the ends of the cone scales.

Needles

Needles in bundles of five; commonly 1 to 1 1/2 inches long; curved; glossy and dark green. Some needles will be speckled with sticky whitish drops or grains or resin. The needles are close together and persist on the branches for many years, 12 to 14 years or even more, making the branches look like a long brush.

Cones

Cone scales are gray-brown or dark brown, and tipped with a slender, curved bristle. Cones are 2 1/2 to 3 1/2 inches long. Some scales have sticky resin drops on the tips, sometimes almost a coat of resin. The seeds are very small: 2 to 3 mm long (less than 1/4 inch), with thin, pale brown, papery wings 1/4 inch long. As in all other pines, there are two seeds per cone scale. In some cases the seeds are not fertilized and the seed will not fill out, leaving only the papery wing between the scales.

Bark

Bark on young trees (up to 5 inch diameter) is thin, smooth, and greyish with a hint of red or even purple, or milky white.

On old trees the bark becomes red-brown, orange-brown, or dark brownish gray, and thicker (1/2 to 3/4 inch), furrowed or broken into flat ridges covered with small scales. In windy locations grey bark on the upwind side on bare limbs may have a reddish-brown tinge.