Backhousia is a small genus of some seven evergreen species of trees and shrubs. They are all endemic to the subtropical and tropical rainforests of coastal eastern Australia. All species have white or cream flowers with prominent stamens. The leaves are smooth-edged and appear in opposite pairs.
Backhousia augustifolia is a dense tree or shrub which is endemic to Queensland. It grows to 6 metres with a spread of 4.5 metres. The leaves have a distinctive fragrance which is released in hot humid weather or when the leaves are crushed. Clusters of white flowers are displayed in spring.
The common names of lemon-scented myrtle or sweet verbena tree are given to Backhousia citriodora. This is another Queensland native. It may reach 10 metres at maturity and have a 5 metre spread. It has foliage from the ground up. The dull green leaves are dense and give off a citrus fragrance when crushed. The flowers are also strongly lemon-scented and creamy white. This tree is cultivated commercially and the oil or citral from its leaves is used for food colouring.
Backhousia hughesii is also known as lime wood or stone wood. It is a large, spreading tree growing to 24 metres with a spread of 10 metres. It is native to far northern Queensland and has grey scaly bark and shiny dark green leaves. Small white flowers with prominent fluffy stamens hang in large clusters at the end of the branchlets. This tree flowers in winter and the blooms are followed by bell-shaped fruits.
The grey myrtle or ironwood (Backhousia myrtifolia) grows to 12 metres and is found in Queensland and New South Wales. It has deep green leaves. The trunks and branches of this species are often utilised as hosts by epiphytic orchids. Fluffy white flowers and persistent green sepals are produced in summer. The young plants of this species need to be protected from frosts.
Backhousia sciadophora or shatterwood is a small to medium-sized tree which is native to New South Wales. It has dense foliage. The new growth is an attractive pink colour which matures to a deep green in summer. The leaves are glossy and oval to elliptical in shape. It displays white blossoms in winter. It has been given the name ‘shatterwood’ for its tendency to shatter or split when cut.
Backhousia do best in rich, well-composted soils which retain moisture as the plants need to have moisture available at all times. Young plants appreciate part-shade although flowering is usually more prolific if the plant is in full sun.
