Norway Maple

Norway maple is the tree that every municipality planted in the 1970s and is now reconsidering. You recognize it by the broad, rounded canopy, the large five-lobed leaves that look like they could be sugar maple until you snap a petiole and see the milky white sap that no native maple produces, and the dense shade beneath it where nothing else grows. It is native to continental Europe and was imported as the urban shade tree that would solve every street planting problem. It did, and then created new ones. The canopy is so dense it suppresses everything underneath, and the prolific seeds germinate aggressively in forest edges, parks, and riparian areas across the region.

In Western Washington, Norway maple is increasingly recognized as invasive. It escapes cultivation readily, establishing in natural areas and outcompeting native understory species through its dense shade and early leaf-out, which gives it a competitive head start over natives. Several cultivars remain in the nursery trade, 'Crimson King' for its purple foliage, 'Columnare' for its narrow form, but the trend is toward removing it from approved street tree lists. If you have an existing Norway maple, it is providing shade and fall color in bronze, gold, red, and yellow, and there is no urgent need to remove a healthy tree. But if you are choosing a new planting, there are better options that do not carry the invasive baggage. Red maple, Freeman maple, or any of the Asian species adapted to this climate will give you what Norway maple gives without the ecological cost.