The genus Corymbia is a recent addition to the scientific nomenclature of plants. Formerly part of the Eucalyptus genus, the bloodwood, spotted gum and ghost gum groups have been given their own genus. This Australian genus consists of over 100 species with most found across the northern half of Australia. There are a few species from temperate eastern Australia and the extreme southwest of Western Australia and a few which occur in New Guinea. Several of the trees belonging to Corymbia have spectacular floral displays, in particular the red-flowering gum (C.ficifolia) and the swamp bloodwood (C.ptychocarpa). Most of the corymbias are favoured by birds.
Corymbia ficifolia (red-flowering gum) is a spectacular specimen tree with many admirers. It is a native of the south-west corner of Western Australia. It has a large, densely leafed crown, a shortish trunk and rough, dark bark. It produces terminal clusters of blooms in summer. The colour of the flowers can be somewhat variable ranging from scarlet to crimson, pink or orange.
Corymbia gummifera, formerly Eucalyptus gummifera, has the common name of red bloodwood. It is native to temperate eastern Australia and has attractive grey-brown, chequered bark. The mature leaves are lance-shaped and dark green on the upper surfaces. The cream flowers are produced in large heads in late summer to autumn. It is a hardy shade tree for temperate climates and tolerates most soil types.
Corymbia citriodora or lemon-scented gum is native to eastern Queensland. It grows to 30 metres and has a slender, straight trunk and high spreading branches. The bark is smooth and powdery, white to grey in colour. The narrow leaves have a sharp lemon fragrance hence the name. White flowers are produced in summer and autumn. It has been a favourite specimen tree for urban parks and gardens but has gained a reputation for suddenly dropping branches. It is utilised for timber, fuel and essential oil.
Corymbia calophyalla or marri is native to south-west Western Australia. It has a dense rounded crown and large clusters of creamy white flowers in summer. The fruiting capsules are large and urn-shaped.
The attractive rough-leafed ghost gum (Corymbia aspera) grows to 10 metres. It is native to northern Australia. It has a single trunk but branches low to the ground. The bark is smooth and powdery but flaky near the base, and may be white, pink or grey in colour. Compound clusters of white flowers are produced in the leaf axils in early summer.
Another beautiful tree is the spotted gum or Corymbia maculata. It can reach 30 metres in height and is native to coastal New South Wales and far eastern Victoria. The bark is smooth and sheds in irregular patches, giving the spotted appearance for which it is named. The bark may be pale grey, pink or cream. The leaves are a dark green and clusters of fragrant white flowers are produced from autumn to winter.
Most of the Corymbia species are fast growing and long living. They are suited for planting as specimen plants and are easy to grow provided the right species is chosen for the intended location. They prefer full sun but susceptibility to frost and moist or dry conditions varies from species to species.