Classification Hierarchies

Classification Hierarchies

In 1735, Carl Linnaeus proposed a hierarchical Tree of Life representing the Kingdoms of Animals and Plants. In 1866, Ernst Haeckel proposed Kingdom Protista for unicellular organisms as seen in microscopes of the day. He later proposed a fourth Kingdom Monera for unicellular organisms whose cells lack nuclei, like bacteria which require more powerful microscopes. Today the generally accepted hierarchy is Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species. For example, Sugar Maple Trees are Acer saccharum, Genus Acer, Species saccharum are in Family Aceraceae, which is in Order Sapindales, which is in Class Angiospermae, which is in Phylum Tracheophyta. Other groups may be put into a classification system like Subphylum which comes between Phylum and Class There are all sorts of different plants. By comparing plants, we can classify them and understand more about them. Clearly Moss is not closely related to an Apple Tree. An Apple Tree seems more like a Pine Tree. Plants are grouped in a hierarchy depending on how closely they are related. At the Two distantly related plants would be put into a separate Phylum from each other. More closely related plants are put into the same Class. Still more similarities form an Order Very closely related plants form a Family Plants that are almost close enough to reproduce are called a Genus. But only plants of the same Species can successfully reproduce. Moss belongs in Phylum Bryophyta whereas Apple Trees belong in Phylum Tracheophyta. A Pine Tree seems more like an Apple Tree than a Moss, but not that close. These trees are put into separate Classes. A Pine Tree is in Class Gymnospermae while Apple Trees are in Class Angiospermae. Angiosperms like Apple Trees are flowering plants and have seeds enclosed within their fruit. Gymnosperms have no flowers or fruits but instead have naked seeds on the surface of their leaves. And so we go on through the ranks of Phylum, Class, Order, Family and Genus until we finish up with one particular plant that we call a Species. [CH] {NR}