Crimson King is a cultivar of the Norway maple, which is a deciduous tree that reaches a height of 60 to 90 feet. Crimson King became popular because of its ornamental purple leaves and was planted widely on city streets. Since becoming naturalized, the Norway maple has been classified as an invasive species because it crowds out native trees, such as the sugar maple, according to Canadian Tree Tours.
Crimson King grows more slowly and is more compact than other Norway maples. It has maroon-yellow flowers that bloom in clusters before the leaves appear in the spring. The flowers give way to samaras, which are helicopter-like seed pods. Since the Norway maple was introduced in the 1700s, it has become the dominant tree in urban areas of North America.
Horticulturists now discourage planting Norway maples. Columbia University explains that the success of the Norway maple comes at the expense of the sugar maple as well as other native plants that can't survive in the shade of its thick canopy. The Norway maple is an economic threat to the maple sugar industry and to the tourist trade, which relies on the colorful autumn displays created in part by the sugar maple's foliage.