Eastern White Pine Tree- Pinus strobus

Eastern White Pine Tree – Pinus strobus
Family Pinaceae: Pine, Cedar, Spruce, Fir
The only five-needle pine native to eastern North America, it is the largest of the eastern conifers.
White Pine bark darkens and thickens as the tree ages, is smooth and gray on young growth. It becomes gray-brown, deeply furrowed with broad ridges of irregularly rectangular, purple-tinged scaly plates. Branches are whorled, few and spreading, with slightly upturned tips. In closed stands, trunks are free of branches over 2/3 of their length. Twigs are slender, flexible, pale red-brown, with rusty hairs when young; aging gray and smooth.

White pines commonly live to 400 years. Height: to 110'  /  Spread: 40'

Needles soft, flexible, blue-green; 2"-4" long, 3-sided, in bundles of five. Evergreen. Buds are heavily resinous and sticky, aromatic. Cones are slender and thornless, 3"-10" long and tapering; each scale usually bears two winged seeds as do all native pines. Roots are widespreading and moderately deep, without a distinct taproot.

Eastern White Pine
The age of this Morton Arboretum Specimen is unknown.

Disease: White Pine Blister Rust (Cronartium ribicola), an introduced fungal disease, has decimated formerly extensive stands. Occurs on a variety of sites from wet bogs and moist streambottoms to dry sand plains and rocky ridges; common on the east shore of lakes where blowdowns create openings for regeneration. Soils: grows on nearly all soil types within its range. Most competitive on fairly infertile sandy soils. On clay or poorly drained soils, occurs only as individuals or in small groups. Grows on fine sandy loams and silty loams on disturbed sites with little hardwood competition.

Sometimes a component of climax forests on sites such as steep slopes and ridge tops where windfall provides regeneration opportunities. Frequently dominates or codominates dryer northern pine forests. In mixed hardwood forests, it often occurs as a scattered superdominant tree towering above the surrounding hardwoods. Lower soil pH limit of 4.0. Seedlings tolerate limited shade from herbaceous ground cover better than other pines.

Fire: Moderately fire resistant; mature trees survive most surface fires due to thick bark, branch-free trunks, and a moderately deep rooting habit. (Younger trees are not as fire resistant.) Needles have relatively low resin content so are not highly flammable. 

Fire, windstorm damage and lightning strikes often cause wounds or kill trees, opening the way for attack by the whitespotted sawyer beetles (below) or other insect pests that are attracted by chemicals emitted by the tree when undergoing severe stress, injury or death. The beetles lay eggs in bark crevices and the larvae mine the cambium layer and pupate in the heartwood. Adult sawyers feed on the tender bark of new shoots, causing the tips to turn brown and die.

Eastern White Pine Foliage
Range: Northern North America, south in mountains. Habitat: Prefers well-drained soils and a cool, humid climate.

Wildlife: Squirrels, chipmunks and mice feed on the seeds and soft needles. Inner bark is a preferred winter food of porcupine and deer browse the twigs. Rabbits may eat the bark of young trees. The seeds are eaten by red squirrels and such birds as crossbills and pine siskins. Pocket gophers graze the roots of seedlings and young trees. Snowshoe hares, white-tailed deer, and cottontails browse the foliage; the bark is eaten by various mammals. Young black bear cubs use large White Pine to climb to safety. Songbirds eat seeds. Bald eagles build nests in living White Pine, usually at a main branch located below the crown top.

Whitespotted Sawyer Beetle – Monochamus scutellatus

Nearly an inch long with antennae 1.5 times that, this  impressive beetle is a pest of coniferous forests across North America. Hosts most often include balsam fir, spruce and especially white pine. Adult female beetles are attracted to chemicals released by injured, dying, or recently killed trees, where they lay their eggs in crevices in the bark or open wounds.

When the eggs hatch, the resultant larvae bore a tunnel through the phloem into the vascular cambium (the still-developing inner bark of the tree that will eventually conduct nutrients and liquids from the roots to the foliage), where they mine beneath the bark and mature through several instars, eventually pupating in a gallery near the surface. Adults exit these galleries in late spring (this specimen was photographed on May 22nd) and early summer, and begin feeding on the tender bark of new twigs, causing the tips to die and turn brownish-red [2].

1. United States Forest Service Silvics Manual Conifers / Pinus strobus
2. USDA Forest Service, Buggwood Network, "Whitespotted Sawyer Monochamus scutellatus"
3. USDA NRCS Threatened and Endangered species
4. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network
5. University of Michigan Native American Ethnobotany
6. Uchytil, Ronald J. 1991. Pinus strobus, Fire Effects Information System, U.S. Department of Agriculture

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