Identify the North American Poplars

Here's how to pinpoint trees in the willow family (Salicaceae).

Cottonwood leaf Cottonwood leaf on volcani...
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The genus Populus' most common North American natives include one true poplar in the north, four primary species of cottonwoods, and the quaking aspen. Most of the known 35 natural poplar species live in the Northern Hemisphere.

The cottonwoods thrive in an ecosystem associated with riparian and wetland areas in eastern and western North America. The aspens are most comfortable in boreal environments dominated by conifers with aspen being a major broad-leaved species. Balsam poplar (Populus balsamifera) is the northernmost American hardwood and a major deciduous tree in Canada and Alaska.

The Common North American Poplar Species

All have long reproductive catkins (a cluster of single-sex flowers) that appear just before the new leaves of spring and can help in identification. The resulting fruit is a capsule that opens into two to four parts. The tufted seeds are shed in masses of white "cotton" which can cover the ground inches deep. The wind carries these seeds between male and female catkins in order to reproduce.

The leaves of aspen and Eastern cottonwood are deltoids (shaped like a simple triangular delta, not divided in parts), whereas black cottonwood and balsam poplar leaves are ovate (up to three times as long as they are wide, with pointed tip and rounded base). They occur on a branch alternately, are simple (single leaf), and mostly toothed. Many of the leaves are green with silvery-white undersides, so always check that when trying to identify a poplar. This gives them a shimmery appearance when a breeze is blowing. Often you can hear their leaves moving.

Poplar trees typically have grey, white, or sometimes black bark. Often you can see dark "lenticels" or lines in the bark that may appear like horizontal scores. A young white poplar has diamond-shaped markings on the bark that darken with age. As all of these trees age, their bark darkens and gets rougher. Some balsam poplars give off a distinctive fresh balsam scent.

Interesting Facts

  • The Eastern Cottonwood, Populus deltoides, is one of the largest North American hardwood trees. 
  • The aspen has the widest range in the United States. It occurs throughout the eastern United States and throughout Canada.
  • All poplars tend to be fast-growing species that are often use in ornamental gardens and residential landscaping. They can reach full height in 12 years.
  • They have wide canopies that make them great for providing shade. Some are suitable for natural privacy screens and for serving as a windbreak.
  • Yellow poplar or tulip poplar is not a true poplar and not listed here.