Corymbia Papuana

''Corymbia'', commonly known as bloodwoods, is a genus of about one hundred species of tree that, along with ''Eucalyptus'', ''Angophora'' and several smaller groups, are referred to as eucalypts. Until 1990, corymbias were included in the genus ''Eucalyptus'' and there is still considerable disagreement among botanists as to whether separating them is valid. As of January 2020, ''Corymbia'' is an accepted name at the Australian Plant Census.

Description

Eucalypts in the genus ''Corymbia'' are trees, sometimes mallee-like, that either have rough, fibrous or flaky bark, or smooth bark that is shed in small flakes or short strips. Young plants and coppice regrowth have leaves that differ from adult leaves. The adult leaves are arranged alternately (strictly disjunct opposite, but appearing alternate), with oil glands. The flower buds are arranged in groups on a branching peduncle, each branch usually with seven buds, but with the pedicels of differing lengths, so that the inflorescence is flat-topped or convex. The anthers are joined to the filament at their mid-point and open by parallel slits. As in ''Eucalyptus'', the five sepals are fused to form an outer calyptra (or operculum) and the five petals an inner calyptra, the two calyptra being shed separately or together as the flower opens. Also as in ''Eucalyptus'' the fruit is usually a woody capsule, but in this case the disc is always depressed and the valves are always enclosed.

Taxonomy and naming

The genus ''Corymbia'' was first formally described in 1995 by Ken Hill and Lawrie Johnson in the journal '' Telopea''. The type species is '' C. gummifera''. The genus name, ''Corymbia'' is from the Latin word ''corymbus'', meaning "a corymb".

The bloodwoods had been recognised as a distinct group within the large and diverse genus ''Eucalyptus'' since 1867. Molecular research in the 1990s, however, showed that they, along with the rest of the section Corymbia, are more closely related to ''Angophora'' than to ''Eucalyptus'', and are now regarded as a separate genus by the Australian Plant Census. All three genera, ''Angophora'', ''Corymbia'' and ''Eucalyptus'', are closely related, and are generally referred to as "eucalypts".

Botanists Ken Hill and Lawrie Johnson were the first to define the genus ''Corymbia'' in 1995, identifying the bloodwoods, ghost gums and spotted gums as a group distinct from ''Eucalyptus''.

Since 1995, there have been ongoing investigations into the relationships between the genera. Genetic analysis of ETS and ITS sequences of DNA in 2006 by Carlos Parra-O and colleagues of 67 taxa (47 of which were within ''Corymbia'') yielded ''Corymbia'' and ''Angophora'' as each other's closest relatives, with the genus ''Eucalyptus'' as an earlier offshoot. The small genera ''Eucalyptopsis'', ''Stockwellia'' and ''Allosyncarpia'' formed a clade which arose earlier still. In 2009, Parra-O and colleagues added more taxa and published a combined analysis of nuclear rDNA (ETS + ITS) and morphological characters published to clarify relationships within the genus. This confirmed two main clades, which they defined as the subgenera ''Corymbia'' and ''Blakella''.

Species list

Distribution

Species of ''Corymbia'' occur in all mainland states of Australia and in the Northern Territory. There are about 100 species, all endemic to Australia except for four species that also occur in New Guinea, and one that is endemic to that country.

Image:Gumnuts02.jpg, ''Corymbia'', capsules (fruit)
Image:Corymbia flowers.jpg, ''Corymbia'' flowers
Image:Gumnut tree.jpg, ''Corymbia'' capsules (fruit)

References

External links

Lucid Online Player - EUCLID Eucalypts of Australia
( Multi-access key to 917 species/subspecies taxonomy as of December 2009, Includes Corymbias and Angophoras.)

A New Name for the Bloodwood and Ghost Gum Eucalypts

Currency Creek Arboretum Eucalypt Research
at Currency Creek Arboretum

{{Taxonbar, from=Q1439250

Myrtaceae genera
Myrtales of Australia
Ornamental trees
Flora of New Guinea