page_title: Acer platanoides
section_title: Classification and identification
hierarchical_section_title: Acer platanoides / Classification and identification
caption_attribution_description: blühender Ahorn Acer platanoides
context_page_description: Acer platanoides, also called the Emerald Queen Maple or the Norway Maple, is a species of maple native to eastern and central Europe and western Asia, from France east to Russia, north to southern Scandinavia and southeast to northern Iran. It was brought to North America in the mid-1700s as a shade tree. It is a member of the family Sapindaceae.
context_section_description: 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. Other related species in this section include Acer campestre (field maple), Acer cappadocicum (Cappadocian maple), Acer lobelii (Lobel's maple), and Acer truncatum (Shandong maple). From the field maple, the Norway maple is distinguished by its larger leaves with pointed, not blunt, lobes, and from the other species by the presence of one or more teeth on all of the lobes.
  It is also frequently confused with the more distantly related Acer saccharum (sugar maple). The sugar maple is easy to differentiate by clear sap in the petiole (leaf stem); Norway maple petioles have white sap. The tips of the points on Norway maple leaves reduce to a fine "hair", while the tips of the points on sugar maple leaves are, on close inspection, rounded. On mature trees, sugar maple bark is more shaggy, while Norway maple bark has small, often criss-crossing grooves. While the shape and angle of leaf lobes vary somewhat within all maple species, the leaf lobes of Norway maple tend to have a more triangular shape, in contrast to the more squarish lobes often seen on sugar maples. Flowering and seed production begins at ten years of age, however large quantities of seeds are not produced until the tree is 20. As with most maples, Norway maple is normally dioecious (separate male and female trees), occasionally monoecious, and trees may change gender from year to year.
  The fruits of Norway maple are paired samaras with widely diverging wings, distinguishing them from those of sycamore, Acer pseudoplatanus which are at 90 degrees to each other. Norway maple seeds are flattened, while those of sugar maple are globose. The sugar maple usually has a brighter orange autumn color, where the Norway maple is usually yellow, although some of the red-leaved cultivars appear more orange.
  The flowers emerge in spring before the leaves and last 2-3 weeks. Leafout of Norway Maple is tied to photoperiod and initiated when day lengths reach approximately 13 hours, which is generally in April. Leaf drop in autumn is initiated when day lengths fall to approximately 10 hours. Depending on the latitude, leaf drop may vary by as much as three weeks, beginning in the second week of October in Scandinavia and the first week of November in southern Europe. 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. 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. Since Norway Maple's leafout in spring is also tied to photoperiod unlike most North American trees which leaf out based on air temperature, the tree has a competitive advantage in that it may leaf out well before native trees and shrubs since the latter may be delayed by the weather conditions. It is one of the few introduced species that can successfully invade and colonize a virgin forest. By comparison, in its native range, Norway maple is rarely a dominant species and instead occurs mostly as a scattered understory tree.
caption: Tree in flower
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