| Jack pine | |
|---|---|
 | |
| Young jack pine | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Pinus |
| Subgenus: | P. subg.Pinus |
| Section: | P. sect.Trifoliae |
| Subsection: | P. subsect.Contortae |
| Species: | P. banksiana |
| Binomial name | |
| Pinus banksiana | |
 | |
| Native range | |
| Synonyms[3][4][5] | |
| |
Jack pine (Pinus banksiana), also known asgrey pine[6] orscrub pine,[6][7] is aNorth Americanpine.
Its native range inCanada is east of theRocky Mountains from theMackenzie River in theNorthwest Territories toCape Breton Island inNova Scotia, and the north-central and northeast of theUnited States fromMinnesota toMaine, with the southernmost part of the range just into northwestIndiana and northwestPennsylvania.[8]
In the far west of its range,Pinus banksiana hybridizes readily with the closely relatedlodgepole pine (Pinus contorta). The species epithetbanksiana is after the English botanist SirJoseph Banks.[9]
Pinus banksiana ranges from 9–22 m (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 topitch 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 reducedserotiny.[10][11] A population on the Maine coast is apparently not reliant on fire for reproduction,[12] and some stands have developed several age classes.[13] 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.[14]
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 (3⁄4–1+1⁄2 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.[15] Thecones are3–5 cm (1+1⁄4–2 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).[16] The typical case is in a fire, however cones on the lower branches can open when temperatures reach 27 °C (81 °F) due to the heat being reflected off the ground.[17]
Kirtland's warbler (Setophaga kirtlandii), a formerlyendangeredbird, depends on pure stands of young jack pine in a very limited area in the north of theLower andUpper Peninsulas ofMichigan for breeding. Most known nesting areas are limited toCrawford,Oscoda, andOgemaw counties.[18] Mature jack pine forests are usually open andblueberries are often abundant in theunderstory.
Young jack pines are an alternate host forsweet fern blister rust (Cronartium comptoniae). Infectedsweet ferns (Comptonia peregrina) release powdery orange spores in the summer and nearby trees become infected in the fall. Diseased trees show vertical orange cankers on the trunk and galls on the lower branches. The disease does not tend to affect older trees.[19]
Jack pines are also susceptible toscleroderris canker (Gremmeniella abietina). This disease manifests by yellowing at the base of the needles. Prolonged exposure may lead to eventual death of the tree.[19]
Insects that attack jack pine stands include thewhite pine weevil (Pissodes strobi), jack pine sawfly, andjack pine budworm (Choristoneura pinus).[19]
Fossil evidence shows the jack pine survived the glacial period in theAppalachian andOzark Mountains.[20]
Like other species of pine,Pinus banksiana has use as timber, although its wood tends to be knotty and not highly resistant to decay. Products includepulpwood,fuel,decking, andutility poles.[9]
