Invasive Species Identification Sheet - Norway Maple
Norway Maple (Acer platanoides L.)
tree; reaches 50+ feet tall; creates dense shade; leaves remain green late into the fall
opposite leaves have milky juice in stems
fruit is a woody, maple-type, double samara with 2 very widely spread "wings"
in fall and winter, twigs end in a large, green to dark, reddish-purple, turban-shaped bud
The milky sap and the widely-spread wings of its samara distinguish Norway Maple. In contrast to certain other maples, the 2 ovaries (which enclose the seeds where the 2 "wings" of the samara meet) are smooth (not ribbed and not fuzzy). The leaves are 4"-7" across with 5-7 lobes. Horticultural varieties include trees with purplish or green and white variegated leaves. The outline of a Norway Maple leaf could be more easily contained within a circle than could the leaf of a native Sugar Maple (because the Sugar Maple leaf has an extended middle lobe in comparison to the leaves of Norway Maple). The bark of a large Norway Maple does not become deeply furrowed or flaky.
Norway Maple is frequent in urban areas where it is planted as a street tree or invasive in vacant lots. Based on the results of a study in a New Jersey natural area, there is concern that in forests managed for native vegetation, Norway Maple will reproduce more vigorously than the native Sugar Maple, and therefore, may out compete Sugar Maple and native, understory herbs and shrubs as well.