Cyperaceae

The Cyperaceae, commonly known as sedges, are a family of graminoid, monocotyledonous flowering plants. Sedges are widely distributed, with centers of diversity in East Asia, though most species prefer temperate climates. They thrive in many environments, particularly wetlands and poor soils, and ecological communities dominated by sedges are called sedgelands or sedge meadows.

The family comprises around 5,500 described species across about 90 genera, with the genus Carex—the true sedges—being the largest, containing over 2,000 species. Morphologically, sedges can be distinguished from grasses and rushes by their stems, which typically have a triangular cross-section (though exceptions like the round-stemmed tule exist), and by leaves arranged spirally in three ranks, whereas grasses have alternate leaves in two ranks. This structural difference is captured in the mnemonic "sedges have edges." Notable members include the water chestnut (Eleocharis dulcis), the papyrus sedge (Cyperus papyrus), which provided the material for ancient papyrus writing, as well as cotton-grass (Eriophorum), spike-rush (Eleocharis), sawgrass (Cladium), nutsedge or nutgrass (Cyperus esculentus and Cyperus rotundus), white star sedge (Rhynchospora colorata), and umbrella sedge (Cyperus alternifolius).

A key characteristic of the family is the formation of dauciform (carrot-like) roots, an adaptation analogous to cluster roots in Proteaceae that enhances nutrient uptake, particularly phosphorus, from poor soils. While most sedges are wind-pollinated, exceptions such as Cyperus niveus and Cyperus sphaerocephalus are insect-pollinated, featuring more conspicuous flowers. Fossil evidence places prominent sedges at least as early as the Eocene epoch, with earlier remains dating to the Late Cretaceous.