An account of the structure of plants naturally begins with the cell which is the proximate unit of organic structure. The elementary unit of plant structure, as of animal structure, is the cell. Faunistically, although not geographically, the Nearctic and Palaearctic areas must form the two subdivisions of one great unit, for which the  Holarctic region  is now the generally accepted term.
Definition: a subclass considered a phylum of the kingdom Protista in some classifications; includes holozoic or saprozoic flagellates.
Meronyms (parts of eubacteria): flagellum (a lash-like appendage used for locomotion (e.g., in sperm cells and some bacteria and protozoa)) Hyponyms (each of the following is a kind of eubacteria): B; bacillus (aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil) corynebacterium (any species of the genus Corynebacterium) listeria (any species of the genus Listeria)