Botany - Systematics

Systematics

Scientific classification in botany is a method by which botanists group and categorize organisms by biological type, such as genus or species. Biological classification is a form of scientific taxonomy. Modern taxonomy is rooted in the work of Carolus Linnaeus, who grouped species according to shared physical characteristics. These groupings have since been revised to improve consistency with the Darwinian principle of common descent. While scientists do not always agree on how to classify organisms, molecular phylogenetics, which uses DNA sequences as data, has driven many recent revisions along more efficient, evolutionary lines and is likely to continue to do so. Botanical classification belongs to the science of plant systematics. The dominant classification system is called the Linnaean taxonomy. It includes ranks and binomial nomenclature. The classification, taxonomy, and nomenclature of botanical organisms is administered by the International Code of Nomenclature for algae, fungi, and plants (ICN).

The five-kingdom system has largely been superseded by modern alternative classification systems. Textbooks generally begin with the three-domain system: Archaea (originally Archaebacteria); Bacteria (originally Eubacteria); Eukaryota (including protists, fungi, plants, and animals). These domains reflect whether the cells have nuclei or not, as well as differences in the chemical composition of the cell exteriors and ribosomes.

Further, each kingdom is broken down recursively until each species is separately classified. The order is: Domain; Kingdom; Phylum; Class; Order; Family; Genus; Species. The scientific name of an organism is generated from its genus and species, resulting in a single world-wide name for each organism. For example, the Tiger Lily is listed as Lilium columbianum. Lilium is the genus, and columbianum the specific epithet. When writing the scientific name of an organism, it is proper to capitalize the first letter in the genus and put all of the specific epithet in lowercase. Additionally, the entire term is ordinarily italicized or underlined. Phylogenetics is the study of similarities among different species.