Trembling Aspen (Populus tremuloides)

Stand of trembling aspen. Elm Rock Farm, April 2020.

Other Common Names:

  • Quaking aspen, trembling poplar, white poplar

Characteristics:

  • Typically less than 15m, but grows up to 25m. Bark is pale white, with black scarring. The trunks of older trees can become dark and furrowed, especially at the base. Bark tends to split vertically.
  • Leaves are alternate and simple. Nearly round, with an abruptly pointed tip, 4-8 cm in diameter, dark green on top, duller on the bottom, with fine, rounded teeth. Leaves are glabrous (hairless) except for very fine hair around the margin. 1-2 glands sometimes exist at the petiole.
  • Leaves turn bright yellow in the fall.
  • Each leaf has a long, flattened petiole (stem), which doesn’t roll easily between the fingers, 3-7 cm long (can be longer than the leaf), which cause the leaves to flutter vigorously in any breeze.
  • The leaves are variable, with young trees sometimes having large triangular leaves, up to 20cm long.
  • Buds are slightly resinous, conical, reddish-brown, glabrous (hairless), 1cm long (bud size variable).
Young leaves of a trembling aspen. Elm Rock Farm, May 2017

Reproduction:

  • Dioecious (male and female flowers on separate trees.)
  • Male and female flowers are both catkins, appearing in spring, before the leaves. Male flowers have a stalked basal disk with 6-12 stamens. Female flowers a 2-chambered ovary with a pair of stigmata at the tip of the pistil.
  • The fruit is a capsule that splits into two and releases white, cottony seeds in the summer. The seeds are dispersed by wind and water.
  • Like other members of the genus, commonly reproduces via new shoots, creating stands of genetically identical trees (clonal stands)

Similar Species:

  • Large-tooth Aspen (P. grandidentata)
    • Leaves of large-tooth aspen are slightly larger, with larger, coarser teeth.
    • Buds of large-tooth aspen are hairy, unlike those of trembling aspen.
    • Young bark of large-tooth aspen tends to have a greenish hue.
  • Balsam poplar (P. balsamifera)
    • Leavesof balsam poplar are somewhat egg-shaped, with a long tapering tip, while leaves of trembling aspen are rounder with a short pointed tip.
    • Buds of balsam poplar are much larger and more resinous.
    • Leaf stalks of balsam poplar are round, roll easily between the fingers, unlike aspen
  • Eastern Cottonwood (P. deltoides)
    • Typically a much taller tree, growing to 40m
    • Buds are much larger and more resinous than aspen
    • Leaves are conspicuously triangular with a flat base, while leaves of trempling aspen tend to be more round.
  • Silver Poplar (P. alba)
    • Buds are hairy, unlike those of aspen
    • Leaves of silver poplar are usually lobed, with wavy margins and a hairy under-surface.
  • White Birch (Betula papyrifera)
    • The white bark of birch peels away in large strips, unlike aspen
    • Leaf stalks of birch are round, and roll easily between the fingers, unlike aspen
    • Leaves of birch are sharply doubly-serrate, while the leaves of aspen have finely rounded margins

Ecological Role:

  • One of the first trees to inhabit forest areas destroyed by fire.
  • Moose, elk, rabbits, rodents, porcupine, deer, grouse and beaver all eat various parts of aspen (bark, leaves, buds, young shoots, etc)
  • Beavers often use aspen for building dams and huts.
  • Provide food and nesting sites for many birds, in particular, the ruffed grouse.

Edibility:

  • Inner bark
  • Sap
  • Catkins

Other Uses:

  • Important lumber tree, used for pulp, waferboard, pallets, boxes, and plywood.
  • Miscellaneous products such as matchsticks, tongue depressors, ice cream sticks, and chopsticks.

Etymology:

  • “Populus” is a Latin word meaning “the people/the nation,” or denoting a poplar tree. The exact etymology is unclear.
  • “Tremuloides” comes from the Latin word “tremulus,” meaning trembling, in reference to the movement of the leaves in the wind.
  • “Aspen” comes from the Middle English word “asp,” which described the aspen tree. The word is derived from the Proto-Germanic language.

Other:

  • Trembling aspen is the most widely distributed tree in North America.
  • Clonal colonies can grow to massive proportions, and live for incredible lengths. A colony in Utah (named Pando) covers 160 acres. Conservative estimates put its age at around 10,000 years.

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