black cottonwood (Populus trichocarpa)

• Size: Grows to 200' tall and 6' in diameter.

• Leaves: Simple, alternate, deciduous. Triangular; 3"-6" long (but sometimes much larger); green above and white below, often with rusty markings. Margins are smooth or with rounded teeth.

• Fruit: Round capsules on a string; contain numerous tiny cottony seeds.

• Twigs: Stout. Terminal buds are cigar-shaped, sticky, and smelly.

• Bark: Smooth and gray on young trees. Furrowed and ridged on mature trees.

• Distribution: Black cottonwoods are found from southeast Alaska into Baja California and from the Pacific to the Dakotas. But for much of its range, it only grows along rivers and streams, avoiding the hot, dry territory they travel through.
  

quaking aspen (Populus tremuloides)

• Size: Small tree growing to 80' tall and 2' in diameter. Short lived.

• Leaves: Simple, alternate, deciduous. Ovate to round; 2"-3" in diameter; green above and paler below; edges smooth or with rounded teeth. Petioles long and flat.

• Fruit: Cone-shaped capsule with cottony seeds.

• Bark: Greenish-white when young. May turn dark and furrowed with age.

• Distribution: quaking aspen grows in more states than any other tree. However it is only found in scattered areas of Oregon. It occurs in our upper Cascades and eastward.

For more information about these species see "Trees to Know in Oregon".