The plants are classified in a hierarchical system with several ranks (species, genus, family, order, class, phylum)

Each species of plant has a Latin name composed of two words: the first one is the name of genus, the second one is the name of species. Closely related species, which resemble each other, are grouped together in the same genus

     Example: the pedunculate oak (Quercus robur) and the sessile oak (Quercus petraea).

Close genera are grouped in the same family.

     Example: the oaks (genus Quercus) and the beech (genus Fagus) belong to the family Fagaceae.

Close families are grouped together in the same order.

     Example: Fagaceae (beech family) and Betulaceae (family of comprising e.g. the birches, the alders, the hornbeam, the hazel) belong to the order Fagales.

A taxon refers to any level of the classification.