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Invasive Species |
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Tree Killers
Norway Maple
(Acer platanoides)
 Photo 24: Stacey Leicht, University of Connecticut Biology
- large deciduous tree that usually grows to 12-18 m (40-60 ft) with a widely-spreading crown
- leaves are 'maple-shaped' and usually dark green
- leaf stems exude a milky sap when broken
- the small, greenish flowers appear in early spring followed by the developing seeds
- the flattened seeds occur in pairs with widely-spreading wings that help with wind dispersal
- reproduction is by seeds which are produced in abundance and germinate quickly
- can grow in a wide range of conditions
History in Canada
- introduced to North America in the mid-1700's from Eurasia as an ornamental tree
- occurs in southern British Columbia and from southern Ontario east to Newfoundland
- widely available from nurseries
 Photo 25: Leslie J. Mehrhoff, University of Connecticut Impact on Trees
- grows in dense stands that suppress native tree seedlings due to shade
- shallow root system prevents native tree seedlings from establishing
- leaves release toxins that affect soil fungi and microbes
- very shade tolerant and can outcompete native trees, such as Sugar Maple and Red Oak
- leaf out is early in spring and leaf drop is late in the fall giving Norway Maple a long growing season compared to native species
Control
- cutting trunks followed by herbicide application to the cut trunks
- herbicide application to seedlings or young saplings
- several years of control may be needed since the seeds are unaffected by the above methods and seedlings can recolonize an area
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