invasive Norway maple leaf

Norway maple (Acer platanoides). Photo: Rob Routledge, Sault College, Bugwood.org

Updated: April 13, 2021

About Norway maple (Acer platanoides)

Life cycle and background

Norway maple (Acer platanoides) is a broadleaf deciduous tree that grows up to 50+ feet in height and produces copious amounts of seeds and dense shade. Native to Eurasia, it was introduced to the United States in the 1750’s. It was used as a street tree due to its fast-growing nature and tolerance of poor soils and air pollution. In some communities, it was planted heavily when American elms were lost to Dutch Elm Disease. The dense shade of these trees reduces light availability for forest understory plants. The dense root system alters nutrient availability and impedes the growth of other species, resulting in lower plant diversity.

Norway maples produce dark green, deciduous leaves with 5-7 sharply pointed lobes. The leaves are opposite of each other along the stem. Greenish-yellow flowers in clusters are produced in April-May. Young bark is smooth. Mature bark is gray-brown with shallow, interlacing ridges and furrows. Fall color is yellow.

Norway maples can be distinguished from other maples by a white milky sap that exudes when a leaf petiole (stem) is detached from the tree.

white sap from norway maple stem
White sap exudes from stem Photo: Lesli Mehrhoff, University of Connecticut, Bugwood.org

Reproduction

Large quantities of paired winged seeds (samaras) are produced. The “wings” of the samara spread widely to nearly 180 degrees. Seeds mature in September-October and often remain on the tree into winter. Spreads to new areas by seeds and vegetative reproduction.

flowers of norway maple
Photo: Jan Samanek, Phytosanitary Administration, Bugwood.org
winged seeds of norway maple
Photo: Leslie Mehrhoff, University of Connecticut, Bugwood.org

Conditions that favor growth

Tolerates a wide variety of light and soil conditions. Seedlings establish quickly in deciduous forests.

What to plant instead

Red maple (Acer rubrum)

Controlling Norway Maple

References and Resources

Dirr, Michael A. 2009. Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses, Sixth Edition.

Kaufman, Sylvan Ramsey & Wallace Kaufman. 2007. Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species.

Sarver, Matthew, Amanda Treher, Lenny Wilson, Robert Naczi, Faith B. Keuhn. 2008. Mistaken Identity? Invasive Plants and Their Native Look-alikes.  Delaware Department of Agriculture.

Swearingen J., B. Slattery, K. Reshetiloff, and S. Zwicker. 2010. Plant Invaders of Mid-Atlantic Natural Areas, 4th ed. National Park Service and U.S. Fish & Wildlife Service, Washington, DC. 168pp.

Compiled by Christa Carignan, reviewed by Debra Ricigliano, University of Maryland Extension, 10/2018.