Syn: Pinus divaricata (Aiton) Sudworth; P.sylvestris Linnaeus var. divaricata Aiton (Kral 1993). "In western Alberta and in northeastern British Columbia, it is sympatric with P. contorta and forms hybrid swarms with that species" (Kral 1993).
"Trees to 27 m; trunk to 0.6 m diam., straight to crooked; crown becoming irregularly rounded or spreading and flattened. Bark orange- to red-brown, scaly. Branches descending to spreading-ascending, poorly self-pruning; twigs slender, orange-red to red-brown, aging gray-brown, rough. Buds ovoid, red-brown, 0.5-1 cm, resinous; scale margins nearly entire. Leaves 2 per fascicle, spreading or ascending, persisting 2-3 years, 2-5 cm x 1-1.5(2) mm, twisted, yellow-green, all surfaces with fine stomatal lines, margins finely serrulate, apex acute to short-subulate; sheath 0.3-0.6 cm, semipersistent. Pollen cones cylindric, 10-15 mm, yellow to orange-brown. Seed cones maturing in 2 years, shedding seeds soon thereafter or often long-serotinous and shedding seeds only through age or fire, upcurved, asymmetric, lanceoloid before opening, ovoid when open, 3-5.5 cm, tan to light brown or greenish yellow, slick, nearly sessile or short-stalked, most apophyses depressed but increasingly mammillate toward outer cone base; umbo central, depressed, small, sunken centrally, unarmed or with a small, reflexed apiculus. Seeds compressed-obovoid, oblique; body 4-5 mm, brown to near black; wing 10-12 mm. 2n=24. " (Kral 1993).
The closely related species Pinus contorta can be distinguished from 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).
Canada: North West Territories, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Québec, Prince Edward Island, New Brunswick and Nova Scotia; and USA: Minnesota, Wisconsin, Michigan, Illinois, Indiana, Pennsylvania, New York, Vermont, New Hampshire, and Maine. Establishes after fire in boreal forests, tundra transition areas, dry flats and hills, and on sandy soils; at elevations of 0-800 m (Kral 1993). See map at left; see also Thompson et al. (1999). Hardy to Zone 2 (cold hardiness limit between -45.6°C and -40.0°C) (Bannister and Neuner 2001).
Diameter 94 cm, height 17 m, crown spread 19 m, located in Lake Bronson, MN (American Forests 1996).
A crossdated age of 246 years was recently secured for a tree near Blue Lake, Ontario (Girardin et al. 2006).
This species was named in honor of Sir Joseph Banks (1743-1820), president of the Royal Society from 1778 until 1819, and in consequence probably the most influential scientist of his day.
This is one of the most cold-hardy trees known; specimens prehardened to subfreezing temperatures showed no adverse effects from immersion in liquid nitrogen (-196°C) (Sakai and Weiser 1973).
The endangered Kirtland's warbler (Dendroica kirtlandii) is dependent on sizable (larger than 80 ha) stands of young (1.5-4 m tall) P. banksiana forest for breeding habitat. It became endangered due to loss of habitat as fire suppression eliminated young P. banksiana stands from the landscape, and suitable habitat is now maintained (in central Michigan) through an extensive controlled burning program (Mayfield 1953, Griggs 1997). Jack pine is the territorial tree of the North West Territories (Kral 1993).
Girardin, M.-P., J.C. Tardif, M.D. Flannigan and Y. Bergeron. 2006. Synoptic-Scale Atmospheric Circulation and Boreal Canada Summer Drought Variability of the Past Three Centuries. Journal of Climate 19(10):1922-1947.
Griggs, Jack L. 1997. All the birds of North America. New York: Harper Collins.
Lambert, A.B. 1803. A description of the genus Pinus, illustrated with figures, directions relative to the cultivation, and remarks on the uses of the several species. London: J. White.
Mayfield, H.F. 1953. A census of the Kirtland's warbler. The Auk 70: 17-20 (cited in Burns & Honkala 1990).
Sakai, A. and C.J. Weiser. 1973. Freezing resistance of trees in North America with reference to tree regions. Ecology 54:118–126.
Last Modified 2012-11-28