Taxonomy is the science of plant classification. The word taxon refers to any taxonomic entity, regardless of rank. In other words, the plant family Ericaceae is a taxon, the genus Vaccinium is a taxon, and the species Vaccinium angustifolium is a taxon. Plant Taxonomy is an old science that uses the gross morphology of plants to separate them into similar groups. Quite often the characteristics that distinguished the plants become a part of their name.