Acer negundo Seeds | Box Elder

Paired, pale brown Box Elder samaras with long, angled wings, on a plain background — Box Elder (*Acer negundo*): Sapindaceae, native to North America and widely naturalised, and invasive in parts of Europe and Asia.

LATIN NAME: Acer negundo

COMMON NAME: Box Elder, Ashleaf Maple

Plant Profile

Box Elder is a fast-growing deciduous tree of the soapberry family, ten to twenty-five metres tall, with a broad, irregular crown and, unusually for a maple, pinnate leaves of three to seven leaflets that look more like an ash than an acer. Its flowers appear before the leaves in spring, and its paired, winged seeds hang in long chains through the autumn.

It comes from the riverbanks and disturbed ground of North America, where it is one of the first trees to colonise bare soil, and it has been planted and has escaped across the temperate world. In parts of Europe and China it is now listed as invasive, since it seeds freely and grows faster than the native vegetation.

Science & Biotechnology

The species is unusual in Acer for its compound leaves and for being dioecious, with male and female flowers on separate trees. Those two traits have made it a subject in studies of the evolution of leaf form and of breeding systems in maples, and its genome has been sequenced as part of comparative work on the genus.

It is the primary host of the boxelder bug, Boisea trivittata, whose populations build up on the female trees and whose aggregations on warm walls in autumn are a familiar nuisance in North America. The bug does little damage to the tree, but it is one of the best-studied examples of a host-specific insect following a plant through its introduced range.

Uses & Benefits

Its sap can be boiled down to a syrup in the way that maple sap is, though the yield is lower and the flavour coarser, and the tree was used for this by Native American peoples and by settlers. Its light wood is used for crates and for fuel, and it is planted as a quick windbreak and for erosion control.

In the garden it is a tree to plant with caution: it is fast, weak-wooded and short-lived, it seeds prolifically, and its seedlings appear in every crack and border. Where it is native it is a useful pioneer; where it is introduced, it is usually better replaced by a less aggressive species.

Growing from Seed

Sow the samaras in autumn in a pot of loamy compost and leave them outside for the winter; cold, moist conditions even out germination. Sow them fresh, since viability falls quickly, and cover them lightly with compost.

Plant out in sun or part shade in any soil, wet or dry; the tree tolerates both. Water through the first summer only, and expect rapid growth. If the tree is being grown for ornament rather than for shelter, remove the female plants or the seed heads before they ripen, since self-sown seedlings will otherwise colonise the garden.

Our Take

A tough, fast maple that is useful on a riverbank and a nuisance in a border. Grow it where its seedlings can be controlled, and think twice in a region where it is listed as invasive.

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