Taxonomy & nomenclature
The keen field mycologist, who may be asked to take on the responsibilities of Recorder to a local group, is expected to understand how both fungi and plants are classified. How does he or she acquire this knowledge? Popular field guides seldom give information on how species are named, or how they are arranged into genera and families. The science of naming things may be thought to be beyond the interests of the reader. More advanced texts and keys often omit these subjects – possibly on the assumption that users have had a university education and so have an understanding of taxonomy and nomenclature. The following notes offer an introduction to these essential and interesting subjects.
Taxonomy is the science of biological classification. We arrange organisms in a hierarchy of groupings in accordance with our understanding of evolutionary relationships. These groupings or taxa (singular taxon) have an orderly relationship to each other. At the top of the hierarchy is the Kingdom: Animals, Plants, Fungi, Bacteria, Chromista and Protozoa. Bacteria are usually split into Eubacteria and Archaebacteria. Viruses are classified separately as non-cellular organisms. Each Kingdom is arranged into a series of taxa each less generalised than the one above. The table below gives the arrangement for Fungi, taking Agaricus campestris as an example. In some cases these are further sub-divided (or united). For example, classes may be split into subclasses, or united into a super-class. The species is the most fundamental unit of the system, but within some species it is possible to recognise smaller units, such as subspecies, varieties or forms.
Kingdom - Fungi
Phylum - Basidiomycota
Class - Basidiomycetes
Order - Agaricales
Family - Agaricaceae
Genus - Agaricus
Species - campestris
Recent changes in plant taxonomy
Many fungi associate with plant material. When naming ‘associated organisms’ of fungi it is helpful to have some understanding of the taxonomy of the higher plants. The Plant Kingdom has seven divisions (six of them covering sea-weeds and other forms of algae). Green plants are in the phylum Chlorophyta, which is further split into two sub-phyla: Chlorophycotina (more green algae), and Embryophytina (forming embryos and including mainly, but not exclusively, the terrestrial plants). The next taxonomic level is class, but plants are first divided into two superclasses: Bryophyta and Tracheophyta. Bryophyta contains three classes comprising the mosses, liverworts and hornworts.