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Trees growing in a peat bog on the Olympic Peninsula in Washington. P. contorta subsp. contorta is commonly found in bogs throughout its range [C.J. Earle, 1999.04].

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P. contorta in general enjoys a competitive advantage on harsh sites. These trees of subsp. latifolia are growing in the Norris Geyser Basin at Yellowstone Natl. Park [C.J. Earle, 2007.07.22].

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Active pollen cones of a specimen of subspecies contorta growing native at Patrick's Point, California [C.J. Earle, 1999.05].

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A specimen of subspecies contorta growing native at Patrick's Point, California [C.J. Earle, 1999.05].

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Two 3-5 m tall trees of subspecies contorta growing as ornamentals within their native range in Seattle (USA) [C.J. Earle, 1999.03.19].

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P. contorta subsp. latifolia is among the most fire-adapted pines. This shows a burn mosaic above Mammoth, Yellowstone Natl. Park, 1 year post-fire [C.J. Earle, 1989.07.02].

off-site photos

 

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Conservation status

Pinus contorta

Douglas ex Loudon 1838

Common names

Lodgepole pine (Burns and Honkala 1990); beach, western scrub, north coast scrub, sand, shore or knotty pine (Peattie 1950).

Taxonomic notes

Three subspecies: subsp. contorta, subsp. latifolia (Engelm.) Critchfield, and subsp. murrayana (Balfour) Engelmann. These taxa are sometimes treated at the rank of variety (Kral 1993), but almost all researchers actively involved with study into the species recognise them at subspecific rank, observing the substantial genetic and adaptational differences between them (Critchfield 1957; Wheeler and Guries 1982a, 1982b; Wheeler and Critchfield 1985; von Rudloff and Lapp 1987; Aitken and Libby 1994).

A fourth taxon, the Mendocino Sands shore pine, has also been recognised as a subspecies by some of these authors, as subsp. bolanderi (Parlatore) Critchfield, but other studies (Wheeler and Critchfield 1985, Aitken and Libby 1994) have shown that this is less distinct from subsp. contorta "The two subspecies [contorta, bolanderi] did not show the phylogenetic dichotomy in allozyme allelic constitutions expected for subspecific classification" (Aitken and Libby 1994), and it is recognised here as a variety within subsp. contorta, var. bolanderi (Parlatore) Koehne. Those who treat the main subspecies at varietal rank treat bolanderi as a synonym of contorta (Kral 1993).

There is also genetic evidence that subsp. latifolia is separable into two populations, a southern one in the Rocky Mts south of the Pleistocene ice, and a northern one which suvived in ice-free areas (nunataks and larger areas too dry for icefield formation) north of the main ice front (Wheeler and Guries 1982b, Wheeler and Critchfield 1985); these could possibly be distinct at varietal rank but no name has been given to the northern population.

Description

Tree: Shrub or tree to 50 m tall and 90 cm dbh, straight to contorted, with crown varying according to genetic race; lower branches often descending, the upper spreading or ascending. Bark: Brown to gray- or red-brown, platy to furrowed, variable in thickness both between and within populations. Twigs: Slender, multinodal, rough, orange to red-brown, aging darker brown. Leaves: Yellow-green to dark green, 2 per fascicle, spreading or ascending, persisting 3-8 years, 2-8 cm × 0.7-2(-3) mm, twisted, all surfaces with fine stomatal lines, margins finely serrulate, apex blunt to acute or narrowly acuminate; sheath 0.3-0.6(-1) cm, persistent. Buds narrowly to broadly ovoid, dark red-brown, to 1.2 cm, slightly resinous. Pollen cones: Ellipsoid to cylindric, 5-15 mm long, orange-red. Seed cones: Variably asymmetric, lanceoloid to ovoid before opening, broadly ovoid to globose when open, (2-)3-6(-7.5) cm long, tan to pale red-brown, lustrous, nearly sessile or on a peduncle to 2-3 mm long, maturing in 16-20 months, variably serotinous, variably persistent. Cone scales: Apophyses nearly rhombic, variously elongate, cross-keeled, often mammillate toward outer cone base and on inside above middle; umbo central, depressed-triangular, prickle barely elongate to stubby or slender and to 6 mm. Seeds: Compressed, obovoid; body ca. 5 mm, black (infertile seeds often mottled pale to red-brown), wing 10-14 mm. 2n=24 (Critchfield 1957, Kral 1993).

The subspecies of Pinus contorta can identified according to the key shown below (from Kral 1993). Trees near the boundaries between subspecies will often show intermediate traits.

1.

Leaves 2-7 cm × 0.7-0.9(-1.1) mm, dark green; mature trunk with bark evidently furrowed; seed cones strongly asymmetric, strongly recurved, persistent or variously serotinous.

var. contorta

+

Leaves (4-)5-8 cm × (0.7-)1-2(-3) mm, yellow-green; mature trunk with bark not evidently furrowed; seed cones asymmetric to nearly symmetric, recurved to spreading, variously serotinous or soon shed.

2

2.

Seed cones asymmetric, recurved, variously serotinous, long-persistent; mid and lower apophyses mostly much domed; main branches mostly horizontally spreading, not ascending at tip.

var. latifolia

+

Seed cones nearly symmetric, mostly spreading, not serotinous, not persistent; mid and lower apophyses mostly shallowly domed; main branches ascending at tips.

var. murrayana

Pinus contorta can be distinguished from its near relative P. banksiana by its seed cones, which are curved forward on branches, unarmed or with small reflexed apiculi. In P. banksiana the seed cones are spreading to recurved on branches, mostly armed with prickles (Kral 1993).

Distribution and Ecology

W USA, W Canada, Mexico: Baja California Norte, at 0-3500 (-3900) m (Critchfield 1957, Wheeler and Guries 1982). Hardy to Zone 7 (cold hardiness limit between -17.7°C and -12.2°C) (Bannister and Neuner 2001) (I suspect this refers to subsp. contorta). See also Thompson et al. (1999).

The map below shows subsp. contorta in red, latifolia in green, and murrayana in blue. The boundaries are not as clear as shown here; in particular, subsp. latifolia is found on fire-prone sites within the mapped distribution of subsp. contorta, e.g. at Deer Park in the northeastern Olympic Mountains; subsp. contorta occurs at some fire-resistant sites (such as bogs) east of the Cascade crest; and the boundary between these and subsp. murrayana is gradational.

Distribution data from USGS (1999).

"Pinus contorta is fire successional over most of its range and is characterized by prolific seeding and high seed viability in disturbed habitats, often resulting in extremely slow-growing, overly dense stands" (Kral 1993). See the subspecies descriptions for more detailed information.

Big tree

See subsp. murrayana.

Oldest

See subsp. murrayana.

Dendrochronology

See the various subspecies descriptions.

Ethnobotany

See the various subspecies descriptions.

Observations

See the various subspecies descriptions.

Remarks

It has become naturalised in some areas including New Zealand, and more locally in Britain; in New Zealand this has become a serious problem adversely affecting native vegetation (papers in Richardson 1998).

Although contradictory, both the Latin and common names accurately describe the species: members of subsp. contorta, first observed growing near the Pacific Ocean (where David Douglas collected and described the species), are intricately contorted by the effects of wind and salt spray; while trees of subsp. latifolia, the commonest tree in Wyoming and much of the remainder of the Rocky Mountains, grow tall and slender, making them ideal material for the lodge-poles of Plains Indian tipis.

Citations

Aitken, S.N. and W.J. Libby. 1994. Evolution of the pygmy-forest edaphic subspecies of Pinus contorta across an ecological staircase. Evolution 48: 1009-1019.

Critchfield, W.B. 1957. Geographic variation in Pinus contorta. Maria Moors Cabot Foundation (Harvard) Publ. 3.

Loudon, J.C. 1838. Arboretum et Fruticetum Britannicum 4: 2292, figs. 2210, 2211.

von Rudloff, E. and M.S. Lapp. 1987. Chemosystematic studies in the genus Pinus. VI. General survey of the leaf oil terpene composition of lodgepole pine. Canadian Journal of Forest Research 17: 1013-1025.

Wheeler, N.C. and W.B. Critchfield. 1985. The distribution and botanical characteristics of lodgepole pine: biogeographical and management implications. Pp. 1-13 in D.M. Baumgartner (ed.). Lodgepole pine: the species and its management. Pullman, WA: Washington State University.

Wheeler, N.C. and R.P. Guries. 1982a. Population structure, genic diversity, and morphological variation in Pinus contorta Dougl. Canadian Journal of Forest Research 12: 595-606.

Wheeler, N.C. and R.P. Guries. 1982b. Biogeography of lodgepole pine. Canadian Journal of Botany 60: 1805-1814.

See also

Lanner (1983).

FEIS database.

Last Modified 2014-03-29