Syn: Pinus balfouriana Greville & Balfour var. aristata (Engelmann) Engelmann (Kral 1993).
"Trees to 15m; trunk to 1m diam., strongly tapering, twisted; crown rounded, flattened (sheared), or irregular. Bark gray to red-brown, shallowly fissured, with long, flat, irregular ridges. Branches contorted; twigs pale red-brown, aging gray, puberulent, young branches resembling long bottlebrushes because of persistent leaves. Buds ovoid-acuminate, pale red-brown, ca. 1 cm, resinous. Leaves 5 per fascicle, upcurved, persisting 10-17 years, (2-)3-4 cm x 0.8-1 mm, mostly connivent, deep blue-green, with drops and scales of resin, abaxial surface with strong, narrow median groove, adaxial surfaces conspicuously whitened by stomates, margins entire or distantly serrulate, apex conic-acute to conic-subulate; sheath 0.5-1.5 cm, scales soon recurving, shed early. Pollen cones ellipsoid, ca. 10 mm, bluish to red. Seed cones maturing in 2 years, shedding seeds and falling soon thereafter, spreading, symmetric, lance-cylindric before opening, lance-ovoid to ovoid or cylindric when open, 6-11 cm, purple to brown, nearly sessile; apophyses much thickened; umbo central, with triangular base, extended into slender, brittle prickle 4-10 mm. Seeds obliquely obovoid; body 5-6 mm, gray-brown to near black; wing ca. 10-13 mm. 2n=24." (Kral 1993).
Needles of Pinus aristata are usually narrower and sharper than in P.longaeva and P.balfouriana, and the leaves almost always have a narrow, median groove on the abaxial surface (Kral 1993).
USA: Montane to subalpine areas of Colorado, New Mexico and Arizona (the San Francisco Peaks) at elevations of 2300 to 3650 meters (Silba 1986, Kral 1993). See also Thompson et al. (1999). Hardy to Zone 3 (cold hardiness limit between -39.9°C and -34.4°C) (Bannister and Neuner 2001).
Diameter 107 cm, height 23 m, crown spread 12 m. Locality: Carson National Forest, NM. Also: Diameter 112 cm, height 22 m, crown spread 10 m. Locality: Colfax County, NM (American Forests 1996).
Little work has been done. Brunstein (1996) did an interesting study of frost rings over an impressive 2,500 year time span.
An ancient timberline grove can be seen along the Auto Road on Mt. Evans, Colorado. This grove has been somewhat vandalized by wood collectors. A more pristine stand can be found at timberline on the San Francisco Peaks of Arizona, although this requires a half-day walk to visit. The species also occurs as an early successional montane forest tree; in this role, it is plentiful in the western Pikes Peak area or Colorado, from the lower Peak west to the Woodland and Cripple Creek areas.
On the San Francisco Peaks, this species is a principal host for the dwarf mistletoe Arceuthobium microcarpum (Hawksworth and Wiens 1996).
Brunstein, F.C. 1996. Climatic significance of the bristlecone pine latewood frost-ring record at Almagre Mountain, Colorado, U.S.A. Arctic and Alpine Research 28(1): 65-76.
Engelmann, G. 1862. American Journal of Science and Arts ser. 2(34):331.
Brunstein, F.C. 2006. Growth-form characteristics of ancient Rocky Mountain bristlecone pines (Pinus aristata), Colorado. U.S. Geological Survey Scientific Investigations Report 2006-5219, 90 p. Available: http://pubs.usgs.gov/sir/2006/5219/, accessed 2008.01.07.
Schauer, A.J., A.W. Schoettle, and R.L. Boyce. 2001. Partial cambial mortality in high-elevation Pinus aristata (Pinaceae). American Journal of Botany 88:646-652. Available: http://www.amjbot.org/cgi/content/full/88/4/646, accessed 2008.01.07.
Last Modified 2014-12-11