shape, venation, and vestiture (hairs) of the perigynium are important structures for distinguishing Carex species. The fruit of Carex is a dry, one-seeded indehiscent achene or nut which grows within the perigynium. Perigynium features aid in fruit dispersal. Ecology and distribution Carex species are found across most of the world, albeit with few species in tropical lowlands, and relatively few in sub-Saharan Africa. Most (but not all) sedges are found in wetlands – such as marshes, calcareous fens, bogs and other peatlands, pond and stream banks, riparian zones, and even ditches. They are one of the dominant plant groups in arctic and alpine tundra, and in wetland habitats with a water depth of up to . Taxonomy and cytogenetics The genus Carex was established by Carl Linnaeus in his work Species Plantarum in 1753, and is one of the largest genera of flowering plants. Estimates of the number of species vary from about 1100 to almost 2000. Carex displays the most dynamic chromosome evolution of all flowering plants. Chromosome numbers range from n = 6 to n = 66, and over 100 species are known to show variation in chromosome number within the species, with differences of up to 10 chromosomes between populations. Carex has been divided into subgenera in a number of ways. The most influential was Georg Kükenthal's classification using four subgenera – Carex, Vignea, Indocarex and Primocarex – based primarily on the arrangement of the male and female flowers. There has been considerable debate about the status of these four groups, with some species being transferred between groups and some authors, such as Kenneth Kent Mackenzie, eschewing the subgenera altogether and dividing the genus directly into sections. The genus is now divided into around four subgenera, some of which may not, however, be monophyletic: Carex subg. Carex – 1450 species, distributed globally Carex subg. Psyllophora (Degl.) Peterm. (equivalent to Kükenthal's "Primocarex") – 70 species Carex subg. Vignea (P. Beauv. ex T. Lestib.) Peterm. – 350 species, cosmopolitan Carex subg. Vigneastra (Tuckerman) Kükenthal (equivalent to Kükenthal's "Indocarex") – 100 species, tropical and subtropical Asia Fossil record Several fossil fruits of two Carex species have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark. Uses Ornamental Carex species and cultivars are popular in horticulture, particularly in shady positions. Native species are used in wildland habitat restoration projects, natural landscaping, and in sustainable