illinoisensis

Illinoisensis is a Latin adjectival epithet used in biological nomenclature to indicate a connection to the U.S. state of Illinois. In scientific names, illinoensis is added to a genus name to form a species name and is typically interpreted as “from Illinois” or “of Illinois.” The ending is chosen to agree with the Latin grammar of the genus, but the core meaning remains a geographic association.

Etymology and usage. The epithet illinoensis derives from the name of Illinois combined with the standard Latin place-name suffix -ensis, which is used in many taxonomic names to denote origin or residence. It is widely employed across taxa, including plants, animals, and fungi, reflecting the location where the type specimen was collected or where the species was first described. The presence of this epithet does not necessarily indicate that the organism is restricted to Illinois; many such species have broader distributions.

Notable example. A well-known instance is Carex illinoensis, commonly called Illinois sedge, a perennial plant in the Cyperaceae family. It occurs in wetlands and moist habitats across parts of North America, including Illinois, where it was first described.

Broader context. Illinoisensis is one of many geographic epithets used in taxonomy to document a link to a place. Such names help convey historical and biogeographic information about species, even as current distributions may extend well beyond their namesake region.