Scientific Name
Acer rubrum
Prior to about 40 years ago, the fall foliage season in Denver was mostly an affair of yellow and gold. However, the widespread planting of red maple — along with Freeman ‘Autumn Blaze’ maples and the white ash cultivar ‘Autumn Purple’ — has added ample orange, red and purple to the palette.
Red maple, the state tree of Rhode Island, is a very common forest tree in the eastern half of the U.S. and is the only maple whose native range extends all the way from northern Maine to the southern tip of Florida, signaling great inherent adaptability. Along with sugar maple, these trees give New England forests their famous blazing fall color. In Denver, it is the numerous named cultivars of red maple that provide much of the consistently red and orange foliage in the fall.
The trees usually reach about 50 feet in height; any tree much taller flirts with championship status in Colorado. For much of their lives, the bark is thin, smooth and light gray, and it is somewhat susceptible to frost cracking in our sunny winter climate. Also called southwest injury, this occurs when the southwest side of a thin-barked trunk loses cold hardiness during sunny winter afternoons with above-freezing temperatures but cannot readjust when temperatures drop well below freezing a few hours after sunset. As trees age and develop thicker bark, this problem diminishes, but wrapping the trunks of younger trees can be an effective preventive.
Red maple flowers are red and quite showy in early spring. The two-winged seeds, also red, ripen by June and have wings that spread at a relatively narrow angle. Even the leaf stalks are red, and the young twigs have a reddish cast. Unfortunately, like silver maple, this is not a long-lived tree, and 100 years may be a typical lifespan. Aside from that, its only weakness is limited tolerance of alkaline soils, which can result in foliar chlorosis (yellowing).