("robust") in reference to the size and strength of the full-grown tree. The common name of swamp mahogany comes from its preferred habitat of swamps, and its timber's likeness to that of West Indies mahogany (Swietenia mahagoni). Eucalyptus robusta is known as the swamp messmate in Queensland. Swamp stringybark is another common name, and Gulgong and Gnorpin are old names recorded. It is called robusta eucalyptus in the United States, beakpod eucalyptus in Puerto Rico, and mkaratusi in Swahili. Eucalyptus robusta belongs to a group of eight species of spongy red-barked gum trees known as red mahoganies in the section Annulares, and is closely related to the bangalay and red mahogany (E. resinifera). It is distinguished from them by its larger flowers and fruit. The latter species grows in drier habitats. Eucalyptus robusta often hybridises with forest red gum (E. tereticornis), the resulting plants having been given the name E. patentinervis. Hybrids reported with other species include bangalay, flooded gum (E. grandis), Tasmanian blue gum (E. globulus), woollybutt (E. longifolia) and Bancroft's red gum (E. bancroftii). Distribution and habitat This species occurs in swamps and alongside estuaries in a narrow coastal strip, usually within a few kilometres of the ocean, from Rockhampton, Queensland south to Jervis Bay, New South Wales. It is also found offshore on Great Keppel, Moreton, Fraser and North and South Stradbroke Islands. It is widely planted as a timber tree, and is considered to be invasive in Hawaii and Réunion, and has become naturalised in Florida. It generally grows on heavy clay soils, but is also found on sandy clay and alluvial sand soils. It grows on sand on offshore islands. Found from sea level to altitudes of above sea level, it grows in swamps or areas where the water table is high, generally fresh or brackish in nature. Older plants are able to tolerate salt but seedlings cannot. Eucalyptus robusta can also grow in highly acidic sulphate estuarine soils with a pH as low as 2.5. It is a dominant tree in swamp forests, often growing in pure stands or with other trees such as red mahogany (E. resinifera), red bloodwood (Corymbia gummifera), pink bloodwood (Corymbia intermedia), swamp sheoak (Casuarina glauca), snow-in-summer (Melaleuca linariifolia), swamp paperbark (M. ericifolia) and, less commonly, forest red gum (E. tereticornis). Conservation The species has been formally assessed for the IUCN Red List as "Near Threatened (NT)" as its population