Box Elder tree identification
The Box Elder Acer negundo is a deciduous Maple tree or shrub that has, unusually for a Maple, pinnate elder-like, leaves and wood that is similar to boxwood, hence its name. It is also called the Ash-leafed Maple. It is native to Canada and the USA from the Atlantic Coast to the Rocky Mountains. It was introduced to Britain in 1688 and is commonly found in gardens, parks and streets. Trees have male flowers on one tree and female flowers on another tree. Box Elder tree identification is by pinnate leaf shape, male and female flowers and winged fruit. The Box Elder cultivar ‘Variegatum’ is widely planted. It has attractive white-variegated leaves when first planted, but soon reverts to the wild type. It is a sterile female clone but has spectacular hanging flowers in spring before the leaves. Click on any photo to enlarge it.
Tree in May
Leaves are pinnate with 3 to 7 leaflets. This leaf has 3 leaflets. The leaflets may or may not have lobes.
Lobes can more clearly be seen on this photo of the underside of the terminal leaflet on this 3-leaflet leaf.
The bark is smooth when young but develops vertical cracks when old.
Trees are either male or female. Male flowers, shown here, appear before the leaves in April.
On this tree clusters of female flowers emerge with the leaves and hang down in racemes in mid-April.
Close-up of female flowers in spring. The flowers are wind pollinated. They will develop into winged fruit by mid summer. The wings are already evident and the 2 stigmas are ready to receive pollen.
Fruits in September. Each female flower develops into a winged fruit, called a samara.
Mature buds are silky grey-brown on grey shoots. Lateral buds, like all Maples, are opposite.
New buds are brown on a green shoot.
Tree in January.