Red Maple

Acer rubrum

One of the most common deciduous trees of eastern and central North America, best known for its deep scarlet foliage in autumn. It is used commercially for small-scale maple syrup production and for its premium lumber.

Acer rubrum, the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America.[1] The red maple ranges from southeastern Manitoba east to Newfoundland, south to Florida, and southwest to East Texas. Many of its features, especially its leaves, are quite variable in form. At maturity, it often attains a height around 30 m (100 ft). Its flowers, petioles, twigs, and seeds are all red to varying degrees and it is best known for its brilliant deep scarlet foliage in autumn.

Over most of its range, red maple is adaptable to a very wide range of site conditions, perhaps more so than any other tree in eastern North America. Due to its attractive fall foliage and pleasing form, it is often used as a shade tree for landscapes. It is used commercially on a small scale for maple syrup production and for its medium to high quality lumber.

Though A. rubrum is sometimes easy to identify, it is highly changeable in morphological characteristics. It is a medium to large sized tree, reaching heights of 27 to 38 m (90 to 120 ft) and exceptionally over 41 m (135 ft) in the southern Appalachians where conditions favor its growth. The leaves are usually 9 to 11 cm (3+1⁄2 to 4+1⁄4 in) long on a full-grown tree. The trunk diameter often ranges from 46 to 88 cm (18 to 35 in); depending on the growing conditions, however, open-grown trees can attain diameters of up to 153 cm (60 in). The trunk remains free of branches until some distance up the tree on forest grown trees, while individuals grown in the open are shorter and thicker with a more rounded crown. The bark is a pale grey and smooth when the individual is young. As the tree grows the bark becomes darker and cracks into slightly raised long plates.[2]

The leaves of the red maple offer the easiest way to distinguish it from its relatives. As with all North American maple trees, they are deciduous and arranged oppositely on the twig. They are typically 5–10 cm (2–4 in) long and wide with three to five palmate lobes with a serrated margin. The sinuses are typically narrow, but the leaves can exhibit considerable variation.[3] The upper side of A. rubrum's leaf is light green and the underside is whitish and can be either glaucous or hairy. The leaf stalks are usually red and are up to 10 cm (4 in) long. The leaves can turn a characteristic brilliant red in autumn, but can also become yellow or orange on some individuals. Soil acidity can influence the color of the foliage and trees with female flowers are more likely to produce orange coloration while male trees produce red. The fall colors of red maple are most spectacular in the northern part of its range where climates are cooler.

The twigs of the red maple are reddish in color and somewhat shiny with small lenticels. Dwarf shoots are present on many branches. The buds are usually blunt and greenish to reddish in color, generally with several loose scales. The lateral buds are slightly stalked, and in addition, collateral buds may be present, as well. The buds form in fall and winter and are often visible from a distance due to their large size and reddish tint. The leaf scars on the twig are V-shaped and contain three bundle scars.

Red maple is far more abundant today than when Europeans first arrived in North America.[8] Because it can grow on a variety of substrates, has a high pH tolerance, and grows in both shade and sun, A. rubrum is a prolific seed producer and highly adaptable, often dominating disturbed sites. While many believe that it is replacing historically dominant tree species in the Eastern United States, such as sugar maples, beeches, oaks, hemlocks and pines, red maple will only dominate young forests prone to natural or human disturbance. In areas disturbed by humans where the species thrives, it can reduce diversity, but in a mature forest, it is not a dominant species; it only has a sparse presence and adds to the diversity and ecological structure of a forest. Extensive use of red maple in landscaping has also contributed to the surge in the species' numbers as volunteer seedlings proliferate. Finally, disease epidemics have greatly reduced the population of elms and chestnuts in the forests of the US. While mainline forest trees continue to dominate mesic sites with rich soil, more marginal areas are increasingly being dominated by red maple.[4]

[1]  Nix, Steve. "Ten Most Common Trees in the United States". About.com Forestry. Retrieved 8 October 2016.

[2] Mitchell, A. F. (1974). Trees of Britain & Northern Europe. London: Harper Collins Publishers. p. 347. ISBN 0-00-219213-6.

[3]  Seiler, John R.; Jensen, Edward C.; Peterson, John A. "Acer rubrum Fact Sheet". Virginia Tech Dendrology Tree Fact Sheets. Virginia Tech. Retrieved 23 May 2019.

[4] Abrams, Marc D (May 1998). "The Red Maple Paradox". BioScience. 48 (5): 335–364. doi:10.2307/1313374. JSTOR 1313374.