The classification of flowering plant families used at the National Herbarium of New South Wales largely follows the names that are current in the Australian Plant Census
(APC) which aligns with the Angiosperm Phylogeny Group
(APG). Currently the APC is following APG III.
There is now a vast knowledge of genetic information on plant relationships, obtained mostly from sequencing DNA, which organises plants into groups, or "taxa" (such as families, orders) based on their hypothetical evolutionary (phylogenetic) relationships inferred mainly from morphological, anatomical and genetic (DNA-based) comparisons.
The National Herbarium of New South Wales is revising the classification system used to catalogue the taxa of this State in anticipation of the move of the Herbarium to the Australian Botanic Garden . Mount Annan. The families of flowering plants will be arranged following APG IV and the generic, species and subspecific taxon concepts will follow APC. This classification will be reflected in the New South Wales Flora Online - PlantNET.
This new classification will cause major shifts in information at both the generic and family level and many keys to taxa will be updated. The process of key writing and new descriptions of taxa at all levels is underway; however, this is a slow process so the alignments to APG IV will take time.
The following links provide more information:
Australian Plant Census
Angiosperm Phylogeny Website
Flora of Australia
The following link provides a general introduction to DNA, genes and heredity:
A primer on the basics of DNA, genes and heredity