Trees and Shrubs of the Eloise Butler Wildflower Garden

Mountain Maple is a shrub-like tree that will grow to no more than 25 feet usually; it grows in moist acidic soil as an understory tree. The largest Mountain Maple known in the United States as of 2021 is in Smyth County VA, measuring 42 feet high, 28 foot crown spread, and 18 inches in circumference. The Minnesota Big Tree list is empty for this species.

Twigs are yellow-green initially in summer, reddish in winter and spring and have fine hair. The buds have two easily seen outer scales.

Bark is thin, greenish on young stems becoming gray to grayish brown on thicker stems with a warty appearance, but without the greenish-white stripes of Striped Maple, A. pensylvanicum.

Leaves: The typically 3-lobed maple-like leaves are opposite, 3 to 4 inches long and with somewhat coarse teeth (unlike A. pensylvanicum which has fine sharp teeth) and with sharp points to the 3 broadly v-shaped lobes. The delicate veining gives a quilted appearance on the upper surface.

The flowers, appearing in mid to late May, after the leaves unfold, are greenish yellow and clustered on a narrow 3 to 6 inch high erect long-stalked flower stem (a raceme). This upright spike like flower structure led to the species name spicatum. This species is monoecious, that is, the unisexual male and female flowers are on separate racemes but in this species some racemes may have both sexes. The flowers have five narrow sepals, no petals, 8 stamens in the male flowers and the female flower ovary is 2-carpel.

The fruit is a paired winged seed (a samara) about 8 mm high, paired at the top at the stalk; the pair are at less than right angles to each other.

 

Habitat: Mountain Maple occurs in the understory of hardwood forests where the soil is somewhat rich, moist to mesic and the sunlight is dappled until full leaf-out of the canopy trees.

Names: The genus, Acer, is the Latin word for 'maple.' The species spicatum, means 'spike bearing' and in this case refers to the upright flower panicle. The author name for the plant classification - ‘Lam.’ is for Jean-Baptiste Lamarck (1744-1829), French naturalist and biologist, an early proponent of evolution who among other things, published the 3 volume Flore francaise. He is best known for his theory of the inheritance of acquired characteristics. In the 19th Century this species was called Acer montanum. Botanists have recently moved the maples into the Sapindaceae family from the older Aceraceae family.

Comparisons: The most similar species is Striped Maple, Acer pensylvanicum, which has striped bark, the flower racemes are nodding rather than erect and the leaves have finer teeth. Also, Striped Maple is dioecious - separate male and female flowers on separate plants.