Syn: Strobus monticola (Douglas ex D. Don) Rydberg (Kral 1993). One of 23 species in Pinus sect. Quinquefoliae. Evolutionary relationships in the genus are not well understood. Chloroplast DNA data (Liston et al. 2007) suggests that P. monticola is sister to a group containing P. albicaulis and most of the Old World white pines (except P. gerardiana and P. peuce, which are basal in the white pine clade). On the other hand, study of a nuclear DNA locus placed it with more "traditional" associates (based on morphological comparisons) such as P. lambertiana, P. strobus, and P. strobiformis (Syring et al. 2007). Discussion in the latter paper traced inconsistency in nuclear DNA results primarily to incomplete lineage sorting, which is what happens when speciation preserves and perpetuates ancestral polymorphisms. Paradoxically (because pines in general are often thought of as "ancient" and "relictual"), relatively rapid speciation in the white pines has produced a group of species that share many polymorphisms and few monophyletic traits.
Trees 30(70) m tall and 100(250) cm in diameter, straight; crown narrowly conic, becoming broad and flattened. Bark grey and thin, smooth, becoming furrowed into distinctive rectangular to hexagonal scaly plates in large individuals. Branches nearly whorled, spreading-ascending; twigs slender, pale red-brown, rusty puberulent and slightly glandular (rarely glabrous), aging purple-brown or gray, smooth. Buds ellipsoid or cylindric, rust-colored, 0.4-0.5cm, slightly resinous. Needles 5 per fascicle, spreading to ascending, persisting 3-4 years, 4-10 cm x 0.7-1 mm, straight, slightly twisted, pliant, blue-green, abaxial surface without evident stomatal lines, adaxial surfaces with evident stomatal lines, margins finely serrulate, apex broadly to narrowly acute; sheath 1-1.5 cm, shed early. Staminate cones ellipsoid, 10-15 mm, yellow. Ovulate cones maturing in 2 years, shedding seeds and falling soon thereafter, clustered, pendent, symmetric, lance-cylindric to ellipsoid-cylindric before opening, broadly lanceoloid to ellipsoid-cylindric when open, 10-25 cm, creamy brown to yellowish, without purple or gray tints, resinous, stalks to 2 cm; umbo terminal, depressed. Seeds compressed, broadly obovoid-deltoid; body 5-7 mm, red-brown; wing 2-2.5 cm. 2n=24 (Kral 1993, Little 1980).
Western USA: Washington, Montana, Idaho, Nevada, Oregon, California; and Canada: Alberta, British Columbia; to 1000 m in N, and at 1900-3000 m in the S. Occurs in lowland fog forests or on moist mountain soils, occasionally in forested bogs. Usually in mixed conifer forests, occasionally in pure stands (Kral 1993, Little 1980). See also Thompson et al. (1999). Hardy to Zone 4 (cold hardiness limit between -34.3°C and -28.9°C) (Bannister and Neuner 2001, but provenance unknown; see remarks below).
A common garden experiment using quantitative traits and genetic analysis linked to a large selection of climate variables was used by Richardson et al. (2009) to show that there are two major climate response ecotypes in P. monticola, found in trees respectively north and south of an abrupt transition zone in the southern Oregon Cascades. Trees south of this line experience warmer, drier summers, have lower tolerance for low temperatures, and have lower growth potential (there is also a gradient in cold tolerance from maritime to continental sites).
The biggest stem volume is found in the Fish Lake Pine, which grows near Fish Lake in Rogue River National Forest, Oregon. It has a stem volume of 91 m3, a dbh of 205 cm and is 67.7 meters tall. Formerly, all the really big white pines grew in Idaho, but they have been largely destroyed by logging and white pine blister rust. The remaining giant Idaho pines are in the Floodwood State Forest, where you can find the Floodwood Giant (52 m3 stem volume, dbh 201 cm, height 69.2 meters) and the tallest known white pine, reaching 70.7 meters high (Van Pelt 2000).
Harlow and Harrar (1969) report a maximum age of 615 years. The source is not stated, but most of their measurements are from ring counts on stumps.
Once the preferred wood for matches (Kral 1993), it is no longer a major timber tree.
It is the only big pine in western Washington and northwest Oregon, and seems to be easily found in inland coniferous forests throughout that area.
This species is the principal host for the dwarf mistletoe Arceuthobium monticola (Hawksworth and Wiens 1996).
Western white pine is the state tree of Idaho (Kral 1993).
Harlow, W.M., and E.S. Harrar. 1969. Textbook of Dendrology. 5th Edition. McGraw-Hill. pp 313.
Liston, A., M. Parker-Defeniks, J.V. Syring, A. Willyard, and R. Cronin. 2007. Interspecific phylogenetic analysis enhances intraspecific phylogeographical inference: a case study in Pinus lambertiana. Molecular Ecology 16(18):3926-3937.
Richardson, B.A., G.E. Rehfeldt, and M.-S. Kim. 2009. Congruent climate-related genecological responses from molecular markers and quantitative traits for western white pine (Pinus monticola). International Journal of Plant Sciences 170(9):1120-1131.
Syring, J.V., K. Farrell, R. Businsky, R. Cronin, and A. Liston. 2007. Widespread genealogical nonmonophyly in species of Pinus subgenus Strobus. Systematic Biology 56(2):1-19.
Last Modified 2017-01-15