Striped Maple

Acer pensylvanicum
Tuesday, July 20, 2010

Striped Maples are a deciduous, understory species typical of mesic hardwood forests, as well as mixed or spruce-fir forests. They can be classified as either a small tree or a large shrub, because they rarely exceed 9 meters in height. These trees occur up to 1676 meters in elevation, but are most common in this area between 760 and 1370 m. They do best with 71 to 163 cm of precipitation per year, and with a “frost-free” (non-freezing) period in the summer of around 3-7 months. These trees prefer the partial shade found in the understory.

Striped Maples have opposite leaves, which are much larger (on average) than the leaves of red maples. 13-18 cm long, these have three deep lobes, and taper to a point at each tip. The leaves have three main veins, extending from the base of the leaf to the tip of each of these lobes. There are small serrations on the edge of the leaf, and they have a thick leafstalk. These leaves are bright, light green above and slightly paler below; they turn yellow in autumn. The maple gets its name from its bark, which, on young shoots or trunks, is pale green striped with white. This, and its large leaves, are the most distinguishing features of A. pensylvanicum.

Striped Maples can flower as young as 11 years old and can be only one meter tall. They have small, bell-shaped flowers, up to 1 cm wide, with five yellow petals. These occur in the late spring, drooping off of the ends of twigs. Pendulous clusters of flowers grow on shoots up to 15 cm long. The male and female flowers are combined on monoecious plants. The fruit matures in autumn; it is a typical maple “helicopter” or samara. The cluster of flowers becomes a cluster of long-winged, light brown fruits up to 3 cm long, that each contain one seed for wind dispersal. The density of dispersed seeds decreases the farther away one gets from the mother tree.

Striped Maples can be both dioecious (having the flowers of only one sex) and monoecious (having the flowers of both sexes on the same tree). Sex expression is variable, and may change in response to environmental stimuli. Monoecious plants are generally more common. In dioecious plants, there are typically more females than males, as one male can pollinate many females.

Striped Maples are spread across the north-eastern coast of the US, extending north through Maine into southwestern Canada, west as far as Michigan, and south in a stripe through the Appalachian Mountains to northern Georgia.

This cutting was taken in the woods near the Brodies’ cabin. It came from an unusually large tree, more than 12 cm in diameter. The striping is not as apparent on this sample; it is more apparent on the trunks of younger trees. As a tree ages, other characteristics must be used in place of the stripes to identify it.

Article by Hazel Galloway