But who thinks that far ahead when planting a tree?īut the main problem turns out to be its invasive nature. Also, it turns out, for reasons unknown, to be relatively short-lived in North America: only about 50 to 60 years compared to up to 250 years in Europe. Over time, it showed more flaws: its dense root system uplifts and destroys sidewalks, it kills lawns and it suffers severe breakage during storms, causing untold millions of dollars of damage. It certainly looked like a good choice… at first. Also, it’s very tolerant of street conditions: air pollution, compacted soil, road salt, etc. It’s not an unattractive tree: relatively fast-growing, with dense, dark green foliage (or purple or variegated foliage in the case of some of its many cultivars) and a thick trunk. Many varieties of Norway maple have decorative foliage, like this purple-leaved cultivar, Acer plantanoides ‘Schwedleri’. It was planted by the hundreds of thousands across North America and remains, in most areas, the tree most commonly sold in garden centers.

The Norway maple, although largely untested, quickly became the street tree of choice. At that time, North America’s most popular street tree, the American elm ( Ulmus americana), was being decimated by Dutch elm disease and people were looking for a substitute. That’s what happened in the 1950s and 1960s with the massive introduction of the Norway maple ( Acer platanoides) in Eastern North America. Sometimes when you try to solve one problem, you create another. Especially obvious in wet summers, Norway maple is susceptible to infection by a fungus called tar spot Rhytisma acerinum which is ugly but not usually damaging to the tree.Norway maple: a nice, symmetrical shade tree… but with a hidden vice! It is not always fatal, but causes aesthetic problems. The wilting may be localized on one or two branches, but it may affect the entire canopy. Pests and diseases: Norway maples are susceptible to Verticillum wilt, which can cause sudden wilting of the leaves. Further, because it has shallow roots and casts a dense shade, other plants, including grass will not grow beneath it, leaving bare ground. Landscape value and potential for home plantingBecause it threatens native species and ecosystems, it is widely recommended that Norway Maple not be planted. Today it is not only the most common planted tree in Toronto parks, yards and streets, but it has also independently invaded Toronto's remaining natural ecosystems. Due to its tolerance of urban pollution, salt and other stresses it was planted by choice to replace elms destreoyed by Dutch Elm Disease in the mid 20th century. Norway maple is the dominant tree of urban forests in many North American cities, including Toronto. Norway maple's place in Toronto's urban forest Return to top of page Norway maple IN TORONTO Sugar maple bark has vertical ridges that curl on one side while Norway maple bark has shallow, intersecting ridges in a regular, often diamond-shaped pattern. Especially in winter, the two species can be distinguished by the bark. Sugar maple leaves never have 7 lobes the sap is clear, visible when the leaf stalk is broken the dangling flowers have no petals and the pairs of samara wings (keys) are nearly paralell. Norway maple is regularly confused with the native sugar maple ( Acer saccharum).

There are many cultivars of Norway maple, including the popular Crimson King, which has maroon-coloured leaves. See London plane-tree page for comparison of leaf shape. The species name platanoides means resembling a plane tree ( Platanus spp), from Platanus, the classical name for plane tree and oides, meaning resembling. The genus name Acer means sharp, referring to the sharp tips of the leaf lobes of most maples. Now Norway maple has been designated an invasive species because it has encroached on natural forests where its dense shade prevents young sugar maples from growing. Tolerant of pollution and drought, by the mid 20th century it was the most frequently planted in towns and cities. By the 1800s, Norway maple was a popular ornamental tree in North America. Native to Europe, Norway maple was introduced to North America around 1756 by the botanist and nurseryman John Bartram, who was central to the exchange of plant specie between Europe and North America.

Norway maple leaves