Flower:

Male and female flowers are on separate trees (dioecious) in hanging catkins from the leaf axils of 1 year old branches. Male catkins are 1½ to 3½ inches long with tiers of red stamens. Female catkins are 2¼ to 6¼ inches long with reddish stigmas.

Leaves and bark:

Leaves are alternate and simple with a round leaf stalk. The blade is 2½ to 3¾ inches long and 1¼ to 1¾ inches wide, lance-elliptic with a rounded base and long taper to the tip, and small rounded teeth. Both leaf surfaces are smooth, the upper dark green, the lower light green with irregular rusty blotches.

New twigs are green and smooth or with very fine hairs, quickly turning brownish, the second year a rich reddish brown and usually smooth. Buds are large, especially the terminal bud (up to 1 inch long), narrowly conical with a sharp point, reddish brown and glossy from a sticky, aromatic resin that coats them. Bark is smooth and thin, greenish brown to gray on younger branches and upper trunk turning dark gray to nearly black near the base of the trunk, with flat-topped vertical ridges and deep furrows between. The trunk can get up to 24 inches diameter at breast height but typically much smaller.

Fruit:

Fruits is a green, egg-shaped capsule on the long pendulous catkins. Capsules split in two halves releasing the cottony seed.

Notes:

While widespread across the northern two thirds of Minnesota and prominent in the state's northwest aspen parkland, balsam poplar is probably the least readily recognized native poplar by the average Minnesotan. Similar in general growth habit and bark characteristics to the other poplars, it is generally the smallest in stature and can easily be recognized by is broad to narrowly lance-shaped leaves with a round stalk and coppery leaf stains that can give the entire tree a dark yellowish cast, noticeable at some distance. This species produces suckering stems from the roots, forming colonial clumps, especially after top logging or fire. It is sometimes called “balm of Gilead” though this is more specifically a pharmaceutical name given to the sticky, fragrant resin on the buds and twigs, which is noticeable in the air on calm, humid days throughout the growing season but more so in early spring as buds begin to break.