Corymbia K.D.Hill & L.A.S.Johnson is a genus of approximately 96–115 accepted species of trees — and occasionally mallee-like shrubs — in the family Myrtaceae. Commonly known as bloodwoods and spotted gums, corymbias are native almost entirely to Australia, occurring across all mainland states and the Northern Territory, with a small number of species extending into or endemic to New Guinea. They have been widely introduced to tropical and subtropical regions worldwide, including parts of Africa, Asia, the Pacific Islands, and the Americas.
The genus is distinguished from the closely related Eucalyptus by several consistent morphological traits. Bark is either persistent and rough — fibrous or tessellated (the "bloodwoods") — or smooth and shed in polygonal flakes (the "spotted gums"). Leaves are dimorphic: juvenile leaves are opposite, while adult leaves are disjunct-opposite and bear oil glands. Flower buds are grouped in branching structures of typically seven per umbellaster, forming flat-topped or convex corymb-like inflorescences — the feature that gives the genus its name. The fused calyx forms a calyptra at anthesis, stamens are numerous in continuous whorls, the ovary is half-inferior and typically 3-locular, and the fruits are woody capsules with enclosed valves.
Corymbia was formally described in 1995 by Ken Hill and Lawrie Johnson in the journal Telopea, separating the bloodwoods and spotted gums from Eucalyptus, where they had previously been placed. Molecular research in the 1990s demonstrated that this group is more closely related to Angophora than to the true eucalypts, supporting their recognition as a distinct genus. Together, Corymbia, Eucalyptus, and Angophora are still collectively referred to as "eucalypts" in horticulture and ecology. The genus is recognised by the Australian Plant Census (as of January 2020) and by Kew's Plants of the World Online, with the World Checklist of Myrtaceae serving as the primary nomenclatural reference.
Etymology
The genus name Corymbia is derived from the Latin word corymbus, meaning "a corymb" — a flat-topped or convex flower cluster in which the outer flower stalks are longer than the inner ones, bringing all flowers to roughly the same level. The name was chosen by Ken Hill and Lawrie Johnson when they formally described the genus in 1995, referencing the characteristically flat-topped compound inflorescences that distinguish corymbias from the more dome-shaped flower clusters typical of many Eucalyptus species.
Distribution
Corymbia is almost entirely endemic to Australia, with species native to all mainland states — Queensland, New South Wales, Victoria, South Australia, and Western Australia — and the Northern Territory. No native species occur in Tasmania. A small number of species (approximately four) extend into New Guinea, and one species is endemic there. PlantNET NSW gives approximately 115 species globally (all but five Australian endemic); POWO records the native range as South New Guinea and Australia.
The genus has been widely introduced beyond its native range. Cultivated populations are established in tropical and subtropical regions of Africa, Asia, the Pacific Islands, and the Americas. Corymbia citriodora (Lemon-scented Gum) and Corymbia maculata (Spotted Gum) in particular are planted extensively as street and amenity trees in warm-climate countries.
History
Before the 1990s, all species now placed in Corymbia were classified within Eucalyptus, where the bloodwoods had long been recognised as a distinct informal group but not accorded separate generic rank. Molecular phylogenetic work in the early 1990s demonstrated that the bloodwood/spotted-gum clade is sister to Angophora rather than nested within Eucalyptus sensu stricto, undermining the monophyly of Eucalyptus as then delimited. Ken Hill and Lawrie Johnson acted on this evidence by formally publishing Corymbia as a new genus in 1995 (Telopea 6(2–3): 214). The genus was subsequently accepted by the Australian Plant Census, with formal recognition confirmed as of January 2020.
Taxonomy
Corymbia was segregated from Eucalyptus by K.D. Hill and L.A.S. Johnson in 1995 (published in Telopea 6(2–3): 214), with Corymbia gummifera designated as the type species. Prior to this work, all species now placed in Corymbia had been treated as part of Eucalyptus. Molecular phylogenetic studies in the 1990s showed that the bloodwoods and spotted gums form a clade more closely related to Angophora than to the core eucalypts, providing the principal justification for the new genus. The three genera — Corymbia, Eucalyptus, and Angophora — are informally grouped as "eucalypts" and all belong to tribe Eucalypteae in the Myrtaceae.
GBIF (key 3180424) records 161 descendant taxa; POWO accepts 96 species (including hybrid taxa); PlantNET NSW cites approximately 115 species globally. The discrepancy reflects differing treatments of synonyms, hybrids, and subspecific taxa across these databases. The World Checklist of Myrtaceae (Govaerts et al., 2008 and subsequent editions) is the primary nomenclatural reference used by POWO/Kew. Within NSW the genus contains two informal groups: bloodwoods (persistent tessellated bark) and spotted gums (smooth bark shed in polygonal flakes). The genus was formally adopted by the Australian Plant Census in January 2020.
