Pinus albicaulis

whitebark pine


The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom -  Tracheobionta (vascular plants). Superdivision -  Spermatophyta (seed plants).  Division -  Coniferophyta (conifers). Class -  Pinopsida. Order - Pinales. Family - Pinaceae (pine) Genus - Pinus L. (pine). Species - Pinus albicaulis Engelm. (whitebark pine).

Ecology: Whitebark pine (Pinus albicaulis) is a slow-growing, long-lived tree of the high mountains of southwestern Canada and western United States. Whitebark pine grows in the highest elevation forest and at timberline.
On most sites, whitebark pine develops a deep and spreading root system. It is well anchored into the rocky substrate and is seldom uprooted despite its large, exposed crown and the violent winds to which it is subjected. Whitebark pine helps to stabilize snow, soil, and rocks on steep terrain and has potential for use in land-reclamation projects at high elevation.
On a broad range of dry, wind-exposed sites, whitebark pine is a climax or near-climax species that persists indefinitely in association with subalpine fir and other tolerant species because it is hardier, more drought tolerant, more durable, and longer-lived. Even on these severe sites, however, a successional trend may be observable on a small scale: whitebark pine pioneers on an open site and is later surrounded and locally replaced by tolerant fir and hemlock. Whitebark Pine often facilitates the establishment of other tree species by providing shelter from harsh conditions.


Stem: generally prostrate to shrubby when exposed; trunks 1--many, < 26 m, < 1.5 m wide, much wider at base; mature bark gray-white, smooth, thin; mature crown often deformed by wind.

Leaf: 5 per bundle, 3--7 cm, +- curved, dark green, stiff; sheath deciduous.

Seed Cone: sessile, erect, 3.5--9 cm, ovate, purple-brown, generally torn apart, seeds dispersed by animals; scale tip knobs angled, prickled.

Seed: wing persistent on scale.

Ecology: Upper red-fir forest to timberline, especially subalpine forest; Elevation: 2000--3700 m.


The principal disease is the introduced white pine blister rust (caused by Cronartium ribicola). This occurs where adequate moisture permits infection of local Ribes spp.(currant and gooseberry bushes, the rust's alternate hosts) in early summer and prevents drying of the infected Ribes leaves throughout the summer.
Mountain pine beetle (Dendroctonus ponderosae) is by far the most damaging insect in mature stands of whitebark pine. Much of the mature whitebark pine in the northern Rockies was killed by this insect between 1909 and 1940.

The dwarf mistletoes (Arceuthobium spp.) cause severe local mortality. The most widespread species is the limber pine dwarf mistletoe (A. cyanocarpum), which causes extensive damage to whitebark pine on Mount Shasta and some nearby areas of northern California.

Wind breakage of the crowns or holes occurs when unusually heavy loads of wet snow or ice have accumulated on the foliage. This damage is prevalent in large, old trees having extensive heart rot. Snow avalanches also are an important damaging agent in some whitebark pine stands.

Fire effects: Wildfire is an important vegetation recycling force in whitebark pine stands, although long intervals (50 to 300 years or more depending on the site) usually occur between fires in a given grove. Lightning has been the major cause of fires in most stands. Wildfire (enhanced by fuels created by epidemics of Dendroctonus ponderosae in lodgepole and whitebark pine), followed by seed dissemination by Clark's nutcrackers, may be the principal means by which whitebark pine becomes established in the more productive sites near its lower elevational limits.


The large, heavy, wingless seeds are borne in dense, fleshy, egg-shaped cones usually 5 to 8 cm long. The cone is dark purple, turning brown as it cures in late summer. It is unusual among cones of North American pines in remaining essentially closed (indehiscent) after ripening rather than spreading its scales to release seeds. Most of the cones are harvested by animals.

Clark's nutcrackers have an essential role in planting whitebark pine seeds. Nutcrackers can carry as many as 150 whitebark pine seeds in their sublingual (throat) pouch and they cache groups of one to several seeds in the soil at a depth of 2 to 3 cm, suitable for germination. Nutcrackers cached an estimated 33,600 limber pine seeds per hectare in one open, burned area during one summer; a similar pattern of seed caching would be expected for whitebark pine. Whitebark pine seeds sustain these birds and their young much of the year, but a large proportion of the seed caches go unrecovered.

At the upper elevational limit of tree growth, whitebark pine forms islands of shrub-like growth [krummholz]. much of the spread of an individual krummholz plant results from branches extending horizontally from a central point, but also that in some plants these long branches become pressed into the surface soil and have developed large roots, which clearly constitutes layering.

Species Distribution


USDA Plant Database
USDA, NRCS. 2016. The PLANTS Database (, 4 February 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America
Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  19+ vols.  New York and Oxford.

Silvics of North America
Burns, R.M., and B.H. Honkala. 1990. Silvics of North America (Volume 1: Conifers). USDA Forest Service Agricultural Handbook 654.

Intermountain Herbarium
Consortium of Intermountain Herbaria. 2016. http// Accessed on February 04.

Burke Museum Plant Image Collection
The plant image collection at the Burke Museum, University of Washington.

Jepson Manual
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA. $131.95, hardcover; 1600 pages. ISBN-13: 978-0520253124.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97.
Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.