EUCLID is an identification and information system and as such does not purport to be a revisional level treatment of the eucalypts. For the majority of taxa EUCLID reflects the current state of taxonomic knowledge. Contrary taxonomic decisions may have been taken in EUCLID in some instances in which the authors have assessed available information and studied plants in the field and disagree with the concepts of other workers.
The nomenclature adopted in EUCLID largely expands upon that of Chippendale's (1988) account of Eucalyptus and Angophora in the Flora of Australia, in which all eucalypts published to that time were comprehensively treated. Chippendale recognized 513 species in Eucalyptus and 7 species in Angophora. Taxa placed in synonymy or disregarded as hybrids by Chippendale are not further discussed in EUCLID. Many new taxa have been published and whole species groups revised since 1988 by a variety of authors from around Australia. Those published up to June 2019 have been assessed and mostly included in the package, which now incorporates 934 species and subspecies. Where a taxon name has not been accepted the resulting nomenclatural changes can be traced through All Eucalypt Names and a brief explanation found in the notes section of the relevant species fact sheet. Nomenclature follows Australian Plant Name Index (APNI). Taxa accepted by the committee (CHAH) that oversees the compilation of the Australian Plant Census (APC) largely correspond with those in EUCLID but not entirely. Different botanists see things differently. In EUCLID edition 3 (2006) several undescribed species were included using "phrase names", and these are still included in this edition but no new undescribed taxa have been added despite new "phrase name" taxa having been indicated and incompletely published, particularly from Western Australia.
EUCLID Eucalypts of Australia is seen as on-going and when time permits taxonomic revisions published after June 2019 will be considered and, after viewing specimens and hopefully plants in the field, included if sound.
The interactive key within the EUCLID package comes with a Tree view where the taxa are grouped according to phylogenetic relationships.
The phylogenetic arrangement in Tree view for genus Eucalyptus is still based on Ian Brooker's (2000) "A new Classification for the genus Eucalyptus ". For genus Corymbia the informal classification of K.D. Hill & L.A.S. Johnson (1995) "Systematic studies in the eucalypts 7. A revision of the bloodwoods, genus Corymbia (Myrtaceae)" is followed. The classification of Angophora is straightforward and simple.
Dean Nicolle has informally published on-line a "Classification of the Eucalypts (Angophora, Corymbia, Eucalyptus )" version 4 April 2019. This has also provided insight. It can be found at this address: http://www.dn.com.au/Classification-Of-The-Eucalypts.pdf