Acer negundo

Acer negundo, also known as the box elder, boxelder maple, Manitoba maple or ash-leaved maple, is a species of maple native to North America from Canada to Honduras. It is a fast-growing, short-lived tree with opposite, ash-like compound leaves. It is sometimes considered a weedy or invasive species, and has been naturalized throughout much of the world, including South America, Australia, New Zealand, South Africa, much of Europe, and parts of Asia.

Acer negundo is a fast-growing and fairly short-lived tree that grows up to 10–25 metres (35–80 feet) tall, with a trunk diameter of 30–50 centimetres (12–20 inches), rarely up to 1 m (3 ft 3 in) diameter. It often has several trunks and can form impenetrable thickets. The typical lifespan of box elder is 60 - 75 years. Under exceptionally favorable conditions, it may live to 100 years.

The shoots are green, often with a whitish to pink or violet waxy coating when young. Branches are smooth, somewhat brittle, and tend to retain a fresh green color rather than forming a bark of dead, protective tissue. The bark on its trunks is pale gray or light brown, deeply cleft into broad ridges, and scaly.

Unlike most other maples (which usually have simple, palmately lobed leaves), Acer negundo has pinnately compound leaves that usually have three to seven leaflets. Simple leaves are also occasionally present; technically, these are single-leaflet compound leaves. Although some other maples (such as Acer griseum, Acer mandshuricum and the closely related A. cissifolium) have trifoliate leaves, only A. negundo regularly displays more than three leaflets. The leaflets are about 5–10 cm (2–4 in) long and 3–7 cm (1+1⁄4–2+3⁄4 in) wide with slightly serrate margins. Leaves have a translucent light green color and turn yellow in the fall.

The yellow-green flowers are small and appear in early spring, with staminate flowers in clusters on slender pedicels and pistillate flowers on drooping racemes 10–20 cm (4–8 in) long.

The fruit is a schizocarp of two single-seeded, winged samaras on drooping racemes. Each seed is slender, 1–2 cm (1⁄2–3⁄4 in) long, with a 2–3 cm (3⁄4–1+1⁄4 in) incurved wing; they drop in autumn or they may persist through winter. Seeds are usually both prolific and fertile.

Unlike most other maples, A. negundo is fully dioecious and both a male and female tree are needed for reproduction to occur. The male and female flowers appear on separate plants, with males featuring clusters that generally have four flowers together, while females appear as a raceme.

The Box elder is not in the Elder genus Sambucus in the family Adoxaceae. A few botanists treat boxelder maple in its own distinct genus (Negundo aceroides) but this is not widely accepted.^{[citation needed]}