Eucalyptus robusta, commonly known as swamp mahogany or swamp messmate, is a tree native to eastern Australia. It is an important winter-flowering species in eastern Australia, and has been planted extensively in many countries around the world. Its timber is used for firewood and in general construction. Growing in swampy or waterlogged soils, it is up to 30 m (100 ft) high with thick spongy reddish brown bark and dark green broad leaves, which help form a dense canopy. The white to cream flowers appear in autumn and winter. The leaves are commonly eaten by insects, and are a food item for the koala. It is an important winter-flowering species in eastern Australia, and has been planted extensively in many countries around the world. Its timber is used for firewood and in general construction.
Eucalyptus robusta grows as a tree to around 20–30 metres (65–100 ft) tall, with a trunk up to 1 metre (3 ft) in diameter at breast height (dbh). The trunk and branches are covered with thick red-brown bark, which has a spongy feel and is stringy peeling in longitudinal strips. The long irregular branches spread laterally, and form a dense canopy with the broad green leaves. Arranged alternately along the stems, these measure 10–16 centimetres (4–6.4 in) long by 2.7 to 4.5 cm (1.1–1.8 in) wide. The white or cream flowers are clustered in inflorescences of from seven to 13 flowers. The flowers appear anywhere from March to September, and peak over May and June. The buds measure 2 cm by 0.8 cm (0.8 by 0.3 in) wide and are distinctive in that the operculum has a prominent long beak, making them fusiform (spindle-shaped). The woody fruits ripen by May to October.
Specimens of E. robusta were first collected by First Fleet surgeon and naturalist John White, and the species description was published by James Edward Smith in his 1793 collaboration with George Shaw, Zoology and Botany of New Holland. Shortly afterwards, the description was reprinted verbatim in Smith’s A Specimen of the Botany of New Holland, and it is this publication that is usually credited.