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. These have been assessed by the authors of EUCLID and mostly included in the package, which now incorporates 894 taxa. Where a taxon name has not been accepted the resulting nomenclatural changes can be traced through All Eucalypt Names and an explanation found in the notes section of the relevant species fact sheet.