Corymbia is a genus of about 113 species of tree that were classified as Eucalyptus species until the mid-1990s. It includes the bloodwoods, ghost gums and spotted gums. The bloodwoods had been recognised as a distinct group within the large and diverse Eucalyptus genus since 1867. Molecular research in the 1990s, however, showed that they, along with the rest of the Corymbia section, are more closely related to Angophora than to Eucalyptus, and are probably best regarded as a separate genus. All three genera - Angophora, Corymbia and Eucalyptus - are closely related, often difficult to tell apart, and are still commonly and correctly referred to as "eucalypts". Groups of naturalists and conservationists do not recognise the Corymbia genus and still categorise its species within Eucalyptus