Invasive Plants in Minnesota

Amur Maple is an introduced and invasive small tree, reaching to 20+ feet in height, typically on multiple stems and with a rounded crown about as wide as the tree is tall. Most grown as ornamentals remain shrub size.

The bark is smooth, grayish brown with darker striation furrows.

Twigs are slender, without hair, reddish brown with light colored lenticels. The buds are short and reddish brown, leaf scars are raised.

The leaves are opposite, simple, longer than wide, 2 to 4 inches long, 3 lobed with the middle lobe much longer that the two laterals. The edges of the lobes have some irregular teeth - double serrate. The leaf shape can be quite variable. Leaves in summer are bright green above, paler beneath, and a bright red in fall, although some specimens may be yellow in the Fall.

The inflorescence is a long-stalked cluster of long-stemmed fragrant flowers, the cluster erect at first, becoming pendulous as the samaras develop.

The flowers are bisexual, unlike many of our native maples. These are a pale yellowish-green in color. They appear with the leaves. The flower perianth is hemispheric in shape with 5 greenish-white overlapping calyx lobes, 8 stamens, exserted, with yellow anthers, and a 2-carpel ovary. Petals inconspicuous or absent.

Fruit: Fertile flowers produce paired samaras, about 3/4 to 1 inch long with the pair hanging from their common stalk at a very close angle. These are green initially becoming brown to dark brown at maturity after going through a red phase. Fruit ripens in fall and persists on the tree, frequently over-winter.

Habitat: This is a hardy species which can grow in full sun or partial shade, prefers moist well-drained soils but also handles dryness and alkaline soil. While the plant can spread via suckering, it spreads rapidly by re-seeding.

Names: The genus, Acer, is the Latin word for 'maple.' The species name, ginnala is from the language of the trees native area - eastern Asia, China and Japan. The author name for the plant classification - ‘Maxim.’ refers to Karl Maximovich, (1827-1891) Russian botanist who extensively studied and wrote about the flora of the far east. Botanists have recently moved the maples into the Sapindaceae family from the older Aceraceae family.

Comparisons: The simple 3-lobed leaf is, with the exception of the Box Elder, Acer negundo L., a distinguishing characteristic of this species, but the Box Elder is a much larger tree. The closely paired samaras are also distinctive plus the brilliant red fall color.