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.
Since these organisms that are from the kingdom Protista, subkingdom Protozoa, and all have flagella, they are in the phylum Mastigophora. Not all the genera (pl. for genus) in the phylum Mastigophora are euglena.Euglena is perhaps the most common.Volvox Reproduction. âºSee a closeup of a volvox colony.o me, these are more interesting than the organisms in subkingdom Algae. Subkingdom Algae is divided into five phyla. The division for Algae is based on three things: habitat, organization (single or multiple cells; one phylum has some colonies), and by type of cell wall.