Blue gum is a common name for subspecies or the species in Eucalyptus globulus complex, and also a number of other species of Eucalyptus in Australia. Confusingly, in Queensland it usually refers to Eucalyptus tereticornis, which is known elsewhere as forest red gum.
Gippsland blue gum: Eucalyptus pseudoglobulus (syn. E. globulus subsp. pseudoglobulus)
Inland blue gum: E. leucoxylon
Large-fruited blue gum: E. leucoxylon
Mountain blue gum: E. cypellocarpa, E. deanei
Round-leaved blue gum: E. deanei
South Australian blue gum: E. leucoxylon
Southern blue gum: Eucalyptus bicostata (syn. E. globulus subsp. bicostata)
Spotted blue gum: Eucalyptus maidenii (syn. E. globulus subsp. maidenii)
Sydney blue gum: E. saligna
Tasmanian blue gum: Eucalyptus globulus (syn. E. globulus subsp. globulus)
Victorian blue gum: Eucalyptus bicostata
Other species are sometimes regarded as blue gums such as E. nitens, and the Sydney blue gum (Eucalyptus notabilis).