The Cyperaceae () are a family of graminoid (grass-like), flowering plants known as . The family is large; botanists have described some 5,500 known species in about 90 genus
Distribution
Cyperaceae species are widely distributed with the centers of diversity for the group occurring in
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 s or as
.
Classification
Some species superficially resemble the closely related
Juncaceae and the more distantly related
. 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
Phyllotaxis. 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
Juncaceae or hollow, nodded
Poaceae.
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 (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
daucus (carrot-like) roots that are an alteration in root morphology that researchers regard as analogous to
in
Proteaceae, which help uptake of nutrients such as
phosphorus from poor soil.
[
] Like other members of the order Poales, sedges are mostly
Anemophily, 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 epoch.
[
]
Genera
, 93 genera are accepted by
Kew's Plants of the World Online.
[
]
External links
