Pinus banksiana (Jack Pine)
|Also known as:|
|Life cycle:||perennial woody|
|Habitat:||sun; dry to mesic sandy soil; upland forest, savanna, barrens|
|Bloom season:||May - June|
|Plant height:||30 to 100 feet|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flowers are borne in structures called cones (strobili) with separate male and female cones on the same tree. Male cones are cylindrical, 1/3 to 2/3 inch long, in dense clusters at the base of a candle (new branchlet), the growing bud tip just above. The female strobili form on the upper portion of the new candle, small and egg-shaped, about 3/8 inch long, pinkish colored on a scaly brown stalk.
Leaves and bark:
Leaves are needle-like, ¾ to 2 inches long, in bundles of two that spiral up around the branch, the pair ascending to widely spreading, and often twisted. Needles are rounded on the outside but facing surfaces flattened (D shaped in cross section), or channeled (U shaped in cross section).
The fruit is a hard cone that takes two years to mature. The first year small and egg shaped, about ½ inch long with a short, thick stalk. Cones are 1 to 2 inches long when mature at the end of the second year, typically a blocky horn shape with the tip curled towards the branch, sealed closed by resin (serotinous) until released by heat of fire, though a few cones may open up without such heat.
Jack Pine is Minnesota's smallest native pine and has the shortest needles of all Pinus species in Minnesota. While typically under 70 feet tall, it can attain a height of 100 feet on better soils where it is mixed in with other forest tree species. It is very tolerant of dry, sandy sites where it can form pure, often straggly, stands. A pioneer species, its heat dependent cones allow it to reproduce quickly following a fire, though on sites favorable to other species, it is ultimately replaced.
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- Jack Pine tree
- Jack Pine trees
- a stand of Jack Pine
- cones sealed with resin
- open cone
- comparison of Minnesota pine needles
- comparison of Minnesota pine cones
Photos courtesy Peter M. Dziuk taken in Aitkin, Hubbard and Itasca counties.
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