| Cyperaceae | |
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| Cyperus polystachyos flower head | |
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Cyperaceae Juss.[1] |
| Genera | |
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94, see text[2] | |
The Cyperaceae (/ˌsaɪpəˈreɪsi.iː, -ˌaɪ/) are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large; botanists have described some 5,500 known species in about 90 genera[3][4] – the largest being the "true sedges" (genus Carex),[5][6] with over 2,000 species.[7]
Cyperaceae species are widely distributed, with the centers of diversity for the group occurring in tropical Asia and tropical South America. While sedges grow in almost all environments, many thrive in wetlands, or in poor soils. Ecological communities dominated by sedges are known as sedgelands or as sedge meadows.
Some species superficially resemble the closely related rushes and the more distantly related grasses. Features distinguishing members of the sedge family from grasses or rushes are stems with triangular cross-sections (with occasional exceptions, a notable example being the tule which has a round cross-section) and leaves that are spirally arranged in three ranks. In comparison, grasses have alternate leaves, forming two ranks.[8][9][10]
Some well-known sedges include the water chestnut (Eleocharis dulcis) and the papyrus sedge (Cyperus papyrus), from which the writing material papyrus was made. This family also includes cotton-grass (Eriophorum), spike-rush (Eleocharis), sawgrass (Cladium), nutsedge or nutgrass (Cyperus rotundus, a common lawn weed), white star sedge (Rhynchospora colorata), and umbrella sedge (Cyperus alternifolius), also known as umbrella papyrus
Members of this family are characterised by the formation of dauciform (carrot-like) roots; an alteration in root morphology that researchers regard as analogous to cluster rootsinProteaceae, which help uptake of nutrients such as phosphorus from poor soil.[11] Like other members of the order Poales, sedges are mostly wind-pollinated, but there are exceptions. Cyperus obtusiflorus and Cyperus sphaerocephalus, both with accordingly more conspicuous flowers, are insect-pollinated.[12]
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This section needs expansion. You can help by adding to it. (February 2024)
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Researchers have identified sedges occurring at least as early as the Eocene epoch.[13]
As of 2024[update], 94 genera are accepted in Kew's Plants of the World Online:[2]
Fossil sedges are known from as early as the Eocene 56 to 33.9 million years ago (mya) and modern sedges are very similar to ancient fossils.
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