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The common name, “boxelder,” refers to the resemblance of its leaves to elder (Sambucus) and the use of the soft wood for box making. “Ashleaf maple,” refers to the resemblance to ash (Fraxinus).
Boxelder is a small, deciduous, fast-growing, short-lived tree growing to 20 m tall, with a broad rounded crown. It often branches low into multiple trunks, which may grow almost parallel to the ground, and can form dense thickets. The bark is light brown-gray with shallow fissures, becoming deeply furrowed. Twigs are slender, shiny green, usually glabrous (without hairs), and often have a whitish to pink or violet waxy coating (glaucous) when young. The leaves are opposite, pinnately compound with 3 to 9 leaflets, long-pointed, coarsely toothed and often shallowly lobed. The flowers are yellow-green, about 5 mm long; the species is generally dioecious (functional male and female flowers occur on separate trees; Wagner 1975; Fewless 2011). Fruits are long-stalked clusters of winged nutlets (samaras) in a pair, 2.5-4 cm long.
Boxelder is generally a tree of river bottoms and disturbed sites on heavy, wet or seasonally flooded soils, where it usually follows cottonwood and willow species in colonizing alluvial bottoms. Populations in native habitats have decreased because of clearing of bottomland forest for agriculture, but they have greatly increased in urban areas, where it readily colonizes disturbed sites due to its prolific seed production, wide dispersal, ease of germination, tolerance of cold, drought, and low-oxygen conditions, and fast growth on clay or heavy fill. It frequently grows along fencerows, railroad tracks, ditches, and abandoned lots (Michigan Flora Online 2011).
Boxelder was widely planted in the Great Plains as a shelterbelt tree—its shallow, fibrous root system helped reduce wind erosion and dust storms—but shelterbelts have largely been removed. It was also widely planted in the U.S. as a street tree, and ornamental cultivars have been developed (including forms with variegated leaves and without seeds).
It has been planted in Europe, Australia, and South America as a roadside, park, garden, and shelterbelt tree, and has naturalized widely in disturbed areas and along riverbanks. It is considered invasive in Poland, Germany, Austria, Russia, Latvia, and Lithuania (Mędrzycki 2011), as well as Australia, New Zealand, China, and Chile (USFS 2011).
Boxelder is sometimes confused with poison ivy (Toxicodendron radicans), because its compound leaves often have three leaflets. A key distinction is that boxelder leaves are opposite rather than alternate.
The boxelder bug (Boisea trivittata, family Rhopalidae) commonly associates with boxelder. The insects cause little damage to the trees, but are considered a pest species because they invade human habitation, often in large numbers, with the onset of cold weather (Hahn and Ascerno 2007).