Acer Platanoides - Classification and Identification

Classification and Identification

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 identify by clear sap in the petiole (Norway maple has 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. The seeds of sugar maple are globose, while Norway maple seeds are flattened. 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 tree tends to leaf out earlier than most maples and holds its leaves somewhat longer in autumn.