The classification of flowering plant families used at the National Herbarium of New South Wales (Botanic Gardens Trust) (NSW)
was based on the system of classification developed by R.M. Dahlgren (1980) in an article titled "A revised system of classification of the angiosperms", published in volume 80 of the Botanical Journal of the Linnean Society
. This modern system organises plants into groups, or "taxa" (such as families, orders) based on their supposed evolutionary (phylogenetic) relationships inferred mainly from morphological and anatomical comparisons.
Since the early 1990s, there has been a vast increase in the amount of available genetic information on plant relationships, obtained mostly from sequencing DNA. These new data suggest that some major re-alignments are required at the genus, family and order levels. Currently, NSW is revising the classification system used to catalogue the taxa of this State. The new systematic arrangement will be based on the classification being developed by the Angiosperm Phylogeny Group.
NSW emphasises the plant family level of the full classification, rather than orders or classes, because the familial level is used by many of us to organise our understanding of plant diversity. A full classification hierarchy for the taxa that occur in New South Wales is currently being developed and will be presented on the PlantNET website.
The following links provide in-depth discussion of the current phylogenetic concepts:
Angiosperm Phylogeny Website
The Tree of Life Web Project
Introduction to Phylogenetic Systematics
The following link provides a general introduction to DNA, genes and heredity:
A primer on the basics of DNA, genes and heredity