Flower:

Male and female flowers are on separate trees (dioecious) in hanging clusters (catkins) from the leaf axils of 1 year old branches. Male catkins are 1¼ to 3¼ inches long with tiers of red stamens that mature from the bottom up and are mixed with long, silky hairs. Female catkins are 1¼ to 2¼ inches long with red stigmas that are also mixed in with long silky hairs..

Leaves and stems:

Leaves are alternate and simple with a flat leaf stalk that cause leaves to flutter in the slightest breeze. The blade is 1¼ to 3 inches long and similar in width, broadly oval to nearly round, abruptly tapered to a pointed tip, mostly rounded at the base, with very short, rounded teeth all around the edge. New leaves often have very fine, scattered silky hairs, especially along the edges but these are quickly lost. Both leaf surfaces of mature leaves are hairless, the upper surface waxy and dark green, the lower much paler.

New shoots are green and mostly smooth or briefly with very short, fine hairs. Twigs are reddish brown and shiny, the buds slender round and sharply pointed, the lateral buds often with a tip curled into the branch. Bark is thin and smooth, a creamy greenish white to nearly bright white on branches and trunk. Deeply furrowed dark gray bark forms at the base of the trunk on older trees. While Minnesota's champion tree for this species is nearly 40 inches in diameter at breast height, 24 inches or less is more typical.

Fruit:

The fruits are green, round and conical capsules arranged on the long pendulous catkins. The capsules split into two halves when mature, releasing the cottony seed.

Notes:

Quaking Aspen is the most abundant and widespread tree in Minnesota today and the most common Populus species in North America. The huge stands across northern Minnesota are the result of clear cutting our expansive pine forests a century ago. A pioneer species, it can spread aggressively via root suckers, eventually producing hundreds—if not thousands—of trees, covering acres, all from a single tree. Fire suppression has also allowed it to expand into historical prairie habitats were subsoil moisture is adequate to sustain it through dry periods. In the winter months its bark could be confused with other Populus species but its small, shiny and hairless buds that are not coated with resin distinguishes it from other similar species.