Angophora costata, commonly known as Sydneyred gum, rusty gum or smooth-barked apple, is a species of medium-sized to tall tree that is endemic to eastern Australia. It has smooth bark, lance-shaped leaves arranged in opposite pairs, flower buds usually in groups of three, white or creamy white flowers and ribbed, oval or bell-shaped fruit.
Description
Angophora costata is a tree that typically grows to a height of and forms a lignotuber. It has smooth pinkish or cream-coloured bark that weathers to grey and is shed in small scales. It is the only Angophora to have smooth bark on the trunk. Young plants and coppice regrowth have sessile, elliptical to egg-shaped leaves arranged in opposite pairs with a stem-clasping base, long and wide. Adult leaves are arranged in opposite pairs, glossy green but paler on the lower surface, lance-shaped or curved, long and wide on a petiole long. The flower buds are arranged on the ends of branchlets on a branched peduncle long, each branch of the peduncle with usually three buds on pedicels long. Mature buds are oval to globe-shaped, up to long and wide. There are five sepals up to long and the petals are white to creamy white with a green keel, long and wide. Flowering occurs from October to December. The fruit is a oval or bell-shaped capsule up to long and wide.
Taxonomy and naming
The Sydney red gum was first formally described in 1788 by Joseph Gaertner and given the name Metrosideros costata in his book De Fructibus et Seminibus Plantarum. In 1916, James Britten changed the name to Angophora costata in the Journal of Botany, British and Foreign. In 1986, Gregory John Leach described three subspecies in the journalTelopea and two names have been accepted by the Australian Plant Census:
* Angophora costata Britten subsp. costata has a floral cup and fruit mostly less than wide;
* Angophora costata subsp. euryphylla L.A.S.Johnson ex G.J.Leach has a hairy floral cup and fruit more than wide.
The third subspecies, subsp. leiocarpa is regarded as a synonym of Eucalyptus leiocarpa. Recent genetic work has been published showing Angophora to be more closely related to Eucalyptus than Corymbia, and the name Eucalyptus apocynifolia has been proposed for this species if it were to be placed in the genus Eucalyptus.
Smooth-barked apple grows well in a variety of situations and can be easily grown from seed in a loose, well-drained seed-raising mixture. Some specimens have straight trunk but others have a more branching habit with twisted trunks. The tree sometimes sheds branches and should not be planted close to buildings.
Significant individuals
in the Sydney suburb of Avalon was named after a huge individual, reportedly around 300 years of age. That tree died in the late 20th century. Also in Sydney, the upper Lane Cove River Valley has several large Sydney red gums, one near Conscript Pass was measured at 45 metres tall. The largest known living tree in New Zealand is located at Hobsonville near Auckland.
