Eucalyptus robusta, commonly known as swamp mahogany or swamp messmate, is a tree native to eastern Australia. 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. 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. The leaf-essential oil from Eucalyptus robusta and E. saligna, the latter in two phenologic stages, were analysed by gas chromatography coupled to mass spectrometry (GC-MS). The major constituent in E. robusta oil was the monoterpene alpha-pinene (73.0% of the total amount).