The Cyperaceae () are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

is large; botanists have described some 5,500 known species in about 90

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

the largest being the "true sedges" (genus ''

Carex ''Carex'' is a vast genus of over 2,000 species of grass-like plants in the family (biology), family Cyperaceae, commonly known as sedges (or seg, in older books). Other members of the family Cyperaceae are also called sedges, however those of ge ...

''), with over 2,000 species.

Distribution

Cyperaceae species are widely distributed with the centers of diversity for the group occurring in tropical

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

and tropical

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. While sedges grow in almost all environments, many thrive in

wetlands A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

or in poor soils. Ecological communities dominated by sedges are known as s or as sedge meadows.

Classification

Some species superficially resemble the closely related rushes and the more distantly related

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es. 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 that has a round cross-section) and leaves that are spirally arranged in three ranks. In comparison, grasses have alternate leaves, forming two ranks. This difference leads to the mnemonic "sedges have edges" in order to tell them apart from generally round rushes or hollow, nodded grasses. Some well-known sedges include the water chestnut (''

Eleocharis dulcis ''Eleocharis dulcis'', the Chinese water chestnut or water chestnut, is a grass-like Cyperaceae, sedge native to Asia, tropical Africa, and Oceania. It is grown in many countries for its edible corms, but if eaten uncooked, the surface of the ...

'') and the papyrus sedge (''

Cyperus papyrus ''Cyperus papyrus'', better known by the common names papyrus, papyrus sedge, paper reed, Indian matting plant, or Nile grass, is a species of aquatic plant, aquatic flowering plant belonging to the sedge family Cyperaceae. It is a Hardiness (pla ...

''), from which the writing material

papyrus Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, ''Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'' or ''papyruses'') can a ...

was made. This family also includes cotton-grass ('' Eriophorum''), spike-rush ('' Eleocharis''), sawgrass ('' Cladium''), nutsedge or nutgrass (also called chufa, '' Cyperus esculentus''/'' Cyperus rotundus'', a cultivated crop and common weed), white star sedge ('' Rhynchospora colorata''), and umbrella sedge ('' Cyperus alternifolius''), also known as umbrella papyrus

Features

Members of this family are characterised by the formation of dauciform (carrot-like) roots that are an alteration in root morphology that researchers regard as analogous to cluster roots in

Proteaceae The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genus, genera with about 1,660 known species. Australia and South Africa have the greatest concentr ...

, which help uptake of nutrients such as

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

from poor soil. Like other members of the order Poales, sedges are mostly

wind-pollinated Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including Poaceae, grasses, Cyperaceae, sedges, and Juncaceae, rushes. ...

, but there are exceptions. '' Cyperus niveus'' and '' Cyperus sphaerocephalus,'' both with accordingly more conspicuous flowers, are insect-pollinated.

Evolution

Researchers have identified sedges occurring at least as early as the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

epoch.

Genera

, 93 genera are accepted by

Kew Kew () is a district in the London Borough of Richmond upon Thames. Its population at the 2011 census was 11,436. Kew is the location of the Royal Botanic Gardens ("Kew Gardens"), now a World Heritage Site, which includes Kew Palace. Kew is ...

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

References

External links

*
Cyperaceae
at th
''Angiosperm Phylogeny Website''
{{Authority control Poales families