Norway Maple

Fact SheetTreatmentAcer platanoides

Invader Images

    • Norway maple leaf
    • Norway maple twig
    • Norway maple bark
    • Norway maple fall foliage
    • Norway maple fruit (samara)
    • Norway maple tree form

Common Look-alikes

    • Sugar maple
      Sugar maple leaves have five lobes. The leaf petiole does not produce a white sap when broken.

Identification

Appearance

Acer platanoides is a tree that usually grows to 40-60 ft. (12-18 m) in height, but can reach heights of 100 ft. (30 m). The bark of the tree is grayish and regularly and shallowly grooved.

Foliage

The palmately lobed leaves are opposite and have 5 to 7 sharply acuminate lobes (with large but few teeth). These leaves are 4-7 in. (10-18 cm) wide. The leaf petioles exude a white sap when broken. The leaves are usually green in color, but there are some cultivars that have dark red leaves. The fall color of the green leaves is yellow.

Flowers

The flowers appear in April and May and are yellow-green in color. They are borne in erect, pedunculate, rounded corymbs. Each flower is 0.25 in. (5-6 mm) wide.

Fruit

The pendulous fruit measure 1.5-2 in. (4-5 cm) in length. The fruit are samaras that are green when young and turn yellow, then brown, with age. The samara wings are divergent, reaching nearly 180 degree angle to each other and are dispersed by wind.

Biology

This species is Quarantined: Class B Noxious Weed

Origin

Native to Europe and Asia, Norway maple was first introduced to the United States by the famous Pennsylvania botanist, John Bartram, in 1756. It was seen as a very popular street tree because of its hardiness. However, it has readily spread through New England forests and is now regarded as an invasive species, capable of shading out native trees.

Habitat

Man-made or disturbed sites, forest edges, and forests. 

Life Cycle

The yellowish-green flowers of Norway maple appear in stalked clusters in mid to late April as the leaves are expanding. They are insect pollinated. Fruits mature in late summer into wide-spreading wings that split down the middle. Large numbers of shade-tolerant seedlings are produced. Populations of these trees will also expand locally by vegetative reproduction. 

ecological threat

  • Unlike native tree species, Norway maple hosts very few native caterpillars, reducing an important food source for bird populations
  • Native mammals do not recognize Norway maple seeds as a food source, further reducing native tree populations.
  • Norway maple (Acer platanoides) provides breeding habitat for another highly invasive species, the Asian longhorned beetle (Anoplophora glabripennis), an insect that threatens to significantly reduce North American hardwood forest stands. Research shows female beetles will live longer and produce more fertile eggs on non-native Norway maples than on native red maples (Acer rubrum).

 

Management Options

Mechanical Control

Hand pull - Any time of year when the ground is soft, especially after a rain, hand pull small plants by the base of the stem. Be sure to pull up the entire root system. Hang from a branch to prevent re-rooting. For larger young plants, use a wrenching tool. Continue to monitor the area every year for new seedlings.

Cut stump - Cut plants back in the fall or winter. Wrap a few layers of burlap or thick plastic over the stump and tie tightly with twine or rope. Check covered stumps periodically and cut back any new growth.

Chemical Control

Cut stump - Cut the plant 4 inches above the ground. Use a drip bottle to apply a 18-21% glyphosate solution to the stump within one hour of cutting. This is best done in late summer through winter when plants are transporting resources to their root systems.

Low volume foliar spray - This method is used for dense populations and best left to a contractor. In the fall, when native plants are losing their leaves, spray a 2% glyphosate solution on the entire leaf surface of the plant. In order to avoid drift to native plants, spray only on calm days.

 

**Be careful not to damage or kill nearby native plants when conducting management work. And when using herbicides, always follow the instructions on the label.**

Citations

Photo credit

Norway maple leaf, 5391792, John M. Randall, The Nature Conservancy, Bugwood.org

Norway maple twig, 5509685, T. Davis Sydnor, The Ohio State University, Bugwood.org

Norway maple tree form, 5509686, T. Davis Sydnor, The Ohio State University, Bugwood.org

Norway maple bark, 5499602, David Stephens, Bugwood.org

Fruit (samara), 5509683, T. Davis Sydnor, The Ohio State University, Bugwood.org

Fall foliage, 5509679, T. Davis Sydnor, The Ohio State University, Bugwood.org

Sugar maple, 5032015, Joseph OBrien, USDA Forest Service, Bugwood.org

information credit

GoBotony, Norway maple

Center for Invasive Species and Ecosystem Health, Norway Maple

University of Minnesota Extension