The American Heritage® Dictionary of the English Language: Fourth Edition.
2000.
Taxonomy of Life.
The taxonomic organization of species is hierarchical. Each species belongs to a genus, each genus belongs to a family, and so on through order, class, phylum, and kingdom. Associations within the hierarchy reflect evolutionary relationships, which are deduced typically from morphological and physiological similarities between species. So, for example, species in the same genus are more closely related and more alike than species that are in different genera within the same family.
Carolus Linnaeus, an 18th-century Swedish botanist, devised the system of binomial nomenclature used for naming species. In this system, each species is given a two-part Latin name, formed by appending a specific epithet to the genus name. By convention, the genus name is capitalized, and both the genus name and specific epithet are italicized, for Canis familiaris or simply C. familiaris.
Modern taxonomy recognizes five kingdoms, into which the estimated five million species of the world are divided. This table presents a familiar organism from each kingdom and the names of the taxonomic groups to which it belongs.
Common Name
Kingdom
Phylum*
Class
Order
Family
Genus
Species
Domesticated
Dog
Animalia
(animals)
Chordata
Mammalia
Carnivora
Canidae
Canis
C. familiaris
Sugar Maple
Plantae
(plants)
Magnoliophyta
Rosidae
Sapindales
Aceraceae
Acer
A. saccharum
Bread Mold
Fungi
(fungi)
Zygomycota
Zygomycetes
Mucoralis
Mucoraceae
Rhizopus
R. stolonifer
Tuberculosis
Bacterium
Prokaryotae
(bacteria)
Firmicutes
Actinobacteria
Actinomycetales
Mycobacteriaceae
Mycobacterium
M. tuberculosis
Pond Alga
Protoctista
(algae, molds,
protozoans)
Chlorophyta
Euconjugatae
Zygnematalis
Zygnemataceae
Spirogyra
S. crassa
* In botanical nomenclature, "division" is used instead of "phylum."
