A commented checklist and key for the genus Carex (Cyperaceae) in Peru

Carex is one of the most species-rich genera of vascular plants worldwide and it is a dominant element in cold and temperate regions. However, its diversity in South America is still less understood than in other areas of the World. In Peru, the genus is a key component of high Andean grasslands and wetlands, yet the last comprehensive taxonomic treatment dates back to 1936 when only 18 species were recognised.

Subsequent checklists increased the number to 25, but current estimates remained incomplete and largely based on outdated identifications. Here, we present a taxonomic update of Carex in Peru, based on extensive fieldwork, herbarium studies across major Peruvian and international collections, literature review and complementary records from citizen-science platforms. Our study documents 56 species, including six strict endemics and three subendemics, with Cajamarca emerging as the richest Department (29 species).

Four species are here confirmed for Peru for the first time. We provide an identification key in English and Spanish and updated distribution maps for all species, as well as a preliminary conservation assessment for 24 rare or endemic taxa using IUCN Criteria. Despite its ecological relevance, Carex remains understudied in Peru, with many species overlooked due to collecting biases, inconspicuous morphology and geographic barriers.

Our findings call for integrative taxonomic, ecological and conservation studies to improve the knowledge on Andean Carex and secure their long-term preservation under accelerating climate change.