Box elder, also commonly known as ashleaf maple, Manitoba maple, box-elder maple, and western box-elder, is a small-to-medium-sized tree, reaching heights of 50 to 75 feet, with a trunk diameter up to 4 feet. The trunk is relatively short and tapering, and the crown is spreading and bushy.
Characteristics
Leaf: Opposite, pinnately compound, 3 to 5 leaflets (sometimes 7), 2 to 4 inches long, margin coarsely serrate or somewhat lobed, shape variable but leaflets often resemble a classic maple leaf, light green above and paler below.
Flower: Species is dioecious; yellow-green, in drooping racemes; appearing in spring.
Fruit: Paired V-shaped samaras, 1 to 1 1/2 inches long, in drooping clusters, light tan when ripe in fall, persist throughout winter.
Twig: Green to purplish green, moderately stout, leaf scars narrow, meeting in raised points, often covered with a glaucous bloom; buds white and hairy, lateral buds appressed.
Bark: Thin, gray to light brown, with shallow interlacing ridges; young bark is generally warty.
Form: Medium sized tree to 60 feet, typically with poor form and multiple trunks; sprouts often occur on bole.
ID Features:
- pinnately compound leaves resemble those of Fraxinus, but leaflets are irregularly shaped.
- green twigs with reddish brown upper surface have waxy bloom that can be rubbed off.
- broken twig has a strong, acrid smell.
- buds covered with silky white hairs.
- white, solid pith in twigs.
Distribution
Box-elder has the broadest range of the North American Maples. It is present in every county in Illinois, reaching optimal growth along streams in floodplains where it occurs with other bottomland hardwoods. It extends from Canada to Guatemala (in the mountains), and from New York in the east to Florida, west to southern Texas, northwest across the great plains into Canada. Further west in Colorado and California it occurs on slopes, in valleys, and associated waterways.
Importance to Ecosystem
Boxelder communities provide important habitat for many
wildlife species and protect livestock from temperature extremes in
summer and winter. Many species of birds and squirrels feed on the
seeds of Boxelder. Mule deer and white-tailed deer use it in
the fall as a browse species of secondary importance.
In addition, this tree provides valuable cover for wildlife and livestock, especially in the Great Plains region where quality cover is often lacking. The degree to which this species provides environmental protection during one or more seasons for wildlife species.
Relationship to other Species
Humans: Box-elder wood is light-weight, soft, and not strong. It is used for low quality furniture, paper pulp, interior finishing, and barrel making. Syrup can be made from the sap.
Animals: The seeds are a source of food for birds and mammals, and are important because they stay on the tree through winter, when other food resources are scarce.
Pests:
Boxelder Bug:
The boxelder bug (Leptocoris trivittatus), also called red shouldered bugs, feed on the leaves and seedpods of boxelder trees. Adult boxelder bugs are 1/2 inch long and have distinct red coloration on their wings. Boxelder bugs are not a serious pest of boxelder trees, but they reproduce rapidly on boxelder trees and are a nuisance pest when they make their way into homes. Adult bugs emit a foul odor and stain furniture indoors.
Boxelder Aphid:
Boxedler aphids (Periphyllus negundinis) uses its long, penetrating mouth parts to feed on the vascular tissue of boxelder trees. In large numbers, boxelder aphids can stunt the growth of young trees. Boxelder aphids also secrete a sugar-rich honeydew while feeding that often leads to secondary fungal problems, according to Colorado State University. 
Other interesting facts
- Box-elder and its seedlings grow on a variety of soils. Although it grows best on moist soils, box-elder is drought and cold resistant.
- It can also tolerate flooding for extended periods (up to a month). In bottomlands, it usually has a shallow root system that extends outward. This is an adaptation to unstable soils and the typically low oxygen content of flooded soils.
- Because of its thin bark, box-elder is susceptible to fire, ice, and wind damage.
- Box-elder is a relatively short-lived tree, typically reaching 60 (rarely 100) years of age. It is fast growing when it is young (the first 15 - 20 years).
Sources:
http://www.fs.fed.us/database/feis/plants/tree/aceneg/all.html
http://dendro.cnre.vt.edu/dendrology/syllabus/factsheet.cfm?ID=3
http://plants.usda.gov/core/profile?symbol=ACNE2
Page Drafted By: Julia Giza
?Acer negundo
?Box Elder
Fun Facts:
- Despite their reputation as “trash trees,” several ornamental cultivars are commercially available.
- Trees are hardy in U.S. Department of Agriculture hardiness zones 2 through 9.
- Grows on moist bottomland sites which are seldom subject to
burning. - Flowers from March through May with or before the appearance of
the leaves. - Throughout its range, Boxelder is most often associated
with various species of cottonwood (Populus spp.) and willow (Salix spp.).