slægt

Slægt is a rank in biological classification that groups one or more species believed to be closely related. In Danish and Norwegian usage, slægt corresponds to the taxonomic rank commonly known in English as genus. A slægt sits above species and below the family (familie) in the hierarchy.

Members of a slægt share defining features and are presumed to descend from a common ancestor. Modern classifications emphasize phylogenetic relationships, so genera are often defined or adjusted on the basis of genetic and morphological evidence. Genera may be monophyletic, containing all descendants of a common ancestor, or, in some classifications, are redefined to reflect evolutionary relationships. The boundaries of a slægt can thus change with new data, and some species are left as incertae sedis if their affinities are uncertain.

The name of a slægt is capitalized and used as the first part of a binomial species name. For example, Homo sapiens, Canis lupus, and Rosa canina illustrate how the genus name prefixes the species epithet. In scientific writing the genus name is typically italicized along with the species epithet in many languages, though formatting specifics depend on the style guide.

In summary, a slægt is a fundamental unit of classification that groups closely related species, reflecting shared ancestry and guiding comparisons, nomenclature, and evolutionary studies.