Jack pine
Jack pine
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2187209

Jack pine

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2187209

Jack pine

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Jack pine

Jack pine (Pinus banksiana), also known as grey pine or scrub pine, is a species of North American pine.

Pinus banksiana ranges from 9–22 metres (30–72 ft) in height. Some jack pines are shrub-sized, due to poor growing conditions. They do not usually grow perfectly straight, resulting in an irregular shape similar to pitch pine (Pinus rigida). This pine often forms pure stands on sandy or rocky soil. Many populations are adapted to stand-replacing fires, with the cones remaining closed for many years, until a forest fire kills the mature trees and opens the cones, reseeding the burnt ground. Other populations have not been shaped by regular stand-replacing fires and have reduced serotiny. A population on the Maine coast is apparently not reliant on fire for reproduction, and some stands have developed several age classes. Populations with lower serotiny are often found on soils that are in some way limiting to faster-growing competition, such as soils shallow to bedrock, shallow to water table, or very young soils.

Its leaves are needle-shaped, evergreen, in fascicles of two, needle-like, straight or slightly twisted, stiff, sharp-pointed, light yellowish-green, spread apart; edges toothed and 2–4 cm (341+12 in) long. The bundle-sheath is persistent. The buds are blunt pointed, up to 15 mm long, reddish-brown, and resinous. On vigorous shoots, there is more than one cyclic component. The bark is thin, reddish-brown to gray in color in juvenile stages. As the tree matures it becomes dark brown and flaky. The wood is moderately hard and heavy, weak, light brown colour. The seed cones vary in shape, being rectangular to oval, cone shaped, straight or curved inward. The cones are 3–5 cm (1+14–2 in) long, the scales with a small, fragile prickle that usually wears off before maturity, leaving the cones smooth.

Unusually for a pine, the cones normally point forward along the branch, sometimes curling around it. That is an easy way to tell it apart from the similar lodgepole pine in more western areas of North America. The cones on many mature trees are serotinous. They open when exposed to intense heat, greater than or equal to 50 °C (122 °F).

In the far west of its range, P. banksiana hybridizes readily with the closely related lodgepole pine (P. contorta).

The species epithet banksiana is after the English botanist Sir Joseph Banks.

Its native range in Canada is east of the Rocky Mountains from the Mackenzie River in the Northwest Territories to Cape Breton Island in Nova Scotia, and the north-central and northeast of the United States from Minnesota to Maine, with the southernmost part of the range just into northwest Indiana and northwest Pennsylvania.

Kirtland's warbler (Setophaga kirtlandii), a formerly endangered bird, depends on pure stands of young jack pine in a very limited area in the north of the Lower and Upper Peninsulas of Michigan for breeding. Most known nesting areas are limited to Crawford, Oscoda, and Ogemaw counties. Mature jack pine forests are usually open and blueberries are often abundant in the understory.

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