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FNA | Family List | FNA Vol. 2 | Pinaceae | Pinus

32. Pinus banksiana Lambert, Descr. Pinus. 1: 7, plate 3. 1803.

Jack pine, pin gris

Pinus divaricata (Aiton) Sudworth; P. sylvestris Linnaeus [var.] d divaricata Aiton

Trees to 27m; trunk to 0.6m 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--1cm, resinous; scale margins nearly entire. Leaves 2 per fascicle, spreading or ascending, persisting 2--3 years, 2--5cm ยด 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--0.6cm, semipersistent. Pollen cones cylindric, 10--15mm, 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--5.5cm, 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--5mm, brown to near black; wing 10--12mm. 2 n =24.

Fire successional in boreal forests, tundra transition, dry flats, and hills, sandy soils; 0--800m; Alta., B.C., Man., N.B., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Ill., Ind., Maine, Mich., Minn., N.H., N.Y., Pa., Vt., Wis.

Pinus banksiana reaches its largest size and best form in Canada. In western Alberta and in northeastern British Columbia, it is sympatric with P . contorta and forms hybrid swarms with that species.

Jack pine ( Pinus banksiana ) is the territorial tree of the Northwest Territories.


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