Acer platanoides

[9] Norway maples often cause significant damage and cleanup costs for municipalities and homeowners when branches break off in storms as they do not have strong wood.

[10][11] The Norway maple is a member (and is the type species) of the section Platanoidea Pax, characterised by flattened, disc-shaped seeds and the shoots and leaves containing milky sap.

[citation needed] The fruits of Norway maple are paired samaras with widely diverging wings,[12]: 395  distinguishing them from those of sycamore, Acer pseudoplatanus, which are at 90 degrees to each other.

Leafout of Norway maple occurs roughly when air temperatures reach 55°F (12°C) and there is at least 13 hours of daylight.

Unlike some other maples that wait for the soil to warm up, A. platanoides seeds require only three months of exposure to temperatures lower than 4 °C (40 °F) and will sprout in early spring, around the same time that leafout begins.

Norway maple does not require freezing temperatures for proper growth; however, it is adapted to higher latitudes with long summer days and does not perform well when planted south of the 37th parallel, the approximate southern limit of its range in Europe.

Further, most North American Norway maples are believed descended from stock brought from Germany, at approximately 48°N to 54°N, not the more southerly ecotypes found in Italy and the Balkans that evolved for similar lighting conditions as the continental United States.

The heavy seed crop and high germination rate contributes to its invasiveness in North America, where it forms dense monotypic stands that choke out native vegetation.

The tree is also capable of growing in low lighting conditions within a forest canopy, leafs out earlier than most North American maple species, and its growing season tends to run longer as the lighting conditions of the United States (see above) result in fall dormancy occurring later than it does in the higher latitude of Europe.

By comparison, in its native range, Norway maple is rarely a dominant species and instead occurs mostly as a scattered understory tree.

Norway maple has been widely taken into cultivation in other areas, including western Europe northwest of its native range.

Marie and Sudbury; although not considered reliably hardy northward, it has been established at Kapuskasing and Iroquois Falls, and even at Moose Factory.

[citation needed] It is favored due to its tall trunk and tolerance of poor, compacted soils and urban pollution, conditions in which the sugar maple has difficulty.

[11][20] The cultivars 'Crimson King'[21] and 'Prigold' (Princeton Gold)[22] have gained the Royal Horticultural Society's Award of Garden Merit.

The roots of Norway maples grow very close to the ground surface, starving other plants of moisture.

For example, lawn grass (and even weeds) will usually not grow well beneath a Norway maple, but English ivy, with its minimal rooting needs, may thrive.

Flower, close-up
Tree in flower
Bark
Foliage and fruits; the fruit are an important characteristic for identification of this species
Feral Norway maple in Philadelphia.