The geographic region covered by the eFlora ranges from the Hunter River south to the Shoalhaven River and west to Lithgow. This area equates to the Central Coast Botanical region, the lower portion of the North Coast Botanical region, and the eastern portion of the Central Tablelands Botanical region of the National Herbarium of NSW. The content for the keys, descriptions and glossary are based on the 5th Edition of the Flora of the Sydney Region. (Pellow, Henwood and Carolin; 2009).
The taxonomic content and arrangement of the eFlora reflects the botanical community's current understanding of the groups of plants occurring in the Sydney region. Through the recent use of nucleotide sequences of genes from the chloroplast and the nucleus of representative species of plants, many of our traditionally recognised plant groups have been found to equate to "natural" groups that have had a single evolutionary origin. Such groups are referred to as being monophyletic by botanists.
This research has indicated that some groups of plants are not monophyletic and their definition and membership needs to be changed accordingly. These adjustments sometimes require a change of composition and name for a large group of plants. Alternatively, the data might indicate that a genus should be transferred to a different family so that all the descendents of an ancestor are found in the same family.
An example of a high level change involves the ferns and their relatives. Recent research has indicated that what was traditionally thought to be a phylum comprising only the ferns (Pteridophyta) is not monophyletic. Only when the ferns are combined with two other phyla; the whiskferns (Psilophyta) and the horsetails (Equesitophyta) do we have a monophyletic group. This newly defined group is now recognised as a phylum called Monilophyta or Polypodiopsoda
At lower taxonomic levels (e.g. family and genus) DNA sequencing has also resulted in some changes to group membership. An example of this is seen in the transfer of Hydrocotyle from Apiaceae to Araliaceae. The eFlora has used these changes where possible, and the website will be updated as botanists reach a consensus about what plant groups should be recognised in the Sydney Region.
The plant systematics community of Australia is leading the way in reaching a consensus on plant names and concepts, and the results of this are available through the Australian Plant Census. In the meantime, if you'd like to learn more about the classification of flowering plants you may wish to visit the Angiosperm Phylogeny Website, or the Tree of Life Project.