Pinus aristata

rocky mountain bristlecone pine


The Basics

USFS Plant Database

Rocky Mountain bristlecone pine is a native conifer. Growth habit is varied and mostly dependent upon elevation. Rocky Mountain bristlecone pine forms krummholz at treeline, and grows as a small tree at upper subalpine elevations. On favorable low-elevation sites it often reaches 12 m in height and 75 cm in circumference...Trunks are usually single, but some Rocky Mountain bristlecone pines have multiple trunks. Bark of Rocky Mountain bristlecone pine is thin, about 0.5-1.9 cm thick at maturity...Rocky Mountain bristlecone pines are long lived. They do not attain the extreme old ages that some Great Basin bristlecone pines do, but some Rocky Mountain bristlecone pines reach 1 or 2 millennia in age... Old trees form an irregular crown with upper limbs ascending and lower limbs deflexed. Old trees show vertical strips of dead ribbonwood, many dead branches, and crown die-back.

Rocky Mountain bristlecone pine occurs in early seral and old-growth stages. It usually dominates both new and old-growth forests and woodlands at high elevations... Succession is slow on cold sites dominated by Rocky Mountain bristlecone pine. Baker found that in Colorado, postfire Rocky Mountain bristlecone pine establishment was uneven-aged, with some trees establishing decades after the last fire. Even so, Rocky Mountain bristlecone pine was the most commonly occurring tree in postfire succession in upper subalpine forests.


A dwarf, shrubby, picturesque tree, 12-40 ft. tall. Trunk is short and contorted, bearing stout branches. Blue-green to gray-green, aromatic needles. Bristle-like prickles at the edge of each cone scale. Tree with very short needles crowded into mass suggesting a foxtail and a broad, irregular crown of spreading branches; a low shrub at timberline.


As a shade-intolerant, seral species, Rocky Mountain bristlecone pine is favored in early postfire succession...Fire may be the primary disturbance in Rocky Mountain bristlecone pine-dominated forests. In a study across Rocky Mountain bristlecone pine's range in Colorado, Baker found most Rocky Mountain bristlecone pine regeneration occurred after stand-replacing fire.

Rocky Mountain bristlecone pine can survive low-severity surface fire. It has thin bark and a low branching habit, so it is poorly adapted to survive more severe fire...Surface fire kills Rocky Mountain bristlecone pine seeds exposed on the soil surface. Seeds stored below ground in Clark's nutcracker caches are insulated from fire damage.

Rocky Mountain bristlecone pine is susceptible to white pine blister rust, an exotic fungus that infects 5-needle white pines...blister rust has already infected mature Rocky Mountain bristlecone pines in northern Colorado...Blister rust-infected white pines such as Rocky Mountain bristlecone pine may take from 2 years to decades to succumb, but infection is always fatal. Gooseberries and currants (Ribes spp.) are the primary host of white pine blister rust.


Rocky Mountain bristlecone pine reproduces from seed. Regeneration requirements for successful bristlecone pine establishment are rarely met, but as an extremely long-lived species, Rocky Mountain bristlecone pine has centuries to millennia to wait for favorable regeneration conditions.

Seed Production and Dispersal - Bristlecone pine is monoecious and wind pollinated...Seeds disperse by wind. Clark's nutcrackers also disperse some Rocky Mountain bristlecone pine seed, although they prefer the larger seeds of limber pine and pinyon pines. Clark's nutcrackers are most likely to cache Rocky Mountain bristlecone pine seeds when seed crops of preferred species are poor. Seed dispersal by Clark's nutcrackers has important implications for Great bristlecone pine's genetic structure and ability to establish on disturbed sites such as burns. Clark's nutcrackers bury seeds in caches. A growth form of clumped trees that fuse at the stem is characteristic of establishment resulting from Clark's nutcracker seed dispersal.

Seedling Establishment - Establishment is rare. Rocky Mountain bristlecone pine seedlings usually establish 200 m or more from parent trees. Best germination and establishment occurs on open, bare mineral soil...Rocky Mountain bristlecone pine is slow growing. Trees from 41-51 cm in diameter have been aged at 200 to 250 years.

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, 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.