The leaves of the American Basswood have a distinctive asymmetrical heart (cordate) shape with uneven bases and tapering abruptly into a pointed tip. The margin of the leaf is serrated. The underside of the leaf is pale green with noticeably raised pinnate veins and tufts of tiny hairs at the vein intersections (axils). Leaves are alternately arranged and reach 4″ to 8″ long.
Twig and Bud Identification
The twigs of the American Basswood are slender, somewhat zigzag, and green to red in color with some lenticils. This tree has distinct buds that are often described as being “humpback” since one side typically bulges disproportionately. Furthermore, the buds typically have 2-3 bud scales that are a reddish color and have a false terminal bud.
On younger American Basswoods, the bark is smooth and green to gray; however, as the tree matures, it develops long, narrow ridges and furrows that are dark grey in color.
The fruit of the American Basswood appear in distinct clusters of small, rounded nutlets on a stalk that hang from narrow, elliptical, winged bracts. The purpose of the bracts is to help increase dispersion by acting as a sail. The fruit typically ripens in late fall and will sometimes remain on the tree until early winter.
The flowers of the American Basswood are pale yellow and hang in hairless long-stalked clusters. The flowers typically have 5 petals and are well-known for their fragrance. Furthermore, the flowers usually appear in May or June and are monoecious.