Quaking Aspen and Paper Birch are both fast-growing trees common in Northern Minnesota. While they are similar in some respects, they actually belong to different plant families.
Paper birch (Betula papyrifera) belongs to the birch family, Betulaceae.
Paper birch is distinguished by its white bark that readily peels off of the tree. The leaves of paper birch are oval with irregularly toothed edges
Photos below show paper birches earlier this spring.
Quaking aspen (Populus tremuloides) are in the willow family, Salicaceae.
The bark of young quaking aspen trees is also white, but it does not easily peek off and the bark turns darker as the tree ages. Leafs of quaking aspen are more circular than birch leaves, with less pronounced teeth along their edges.
In late May this year quaking aspens in our area produced a prodigious number of cottony seeds that filled the air, much more than in the last few years. Photos below show the aspen cotton accumulating along the edges of the Paul Bunyan biking trail and show the catkins that release these seeds.
The amount of aspen seed cotton this year was truly remarkable, particularly since aspens reproduce much more effectively from shoots arising along its long lateral roots. Very few aspen seeds survive to produce new trees.