Cyperaceae


The Cyperaceae are a family of graminoid, monocotyledonous flowering plants known as sedges. The family is large; botanists have described some 5,500 known species in about 90 generathe largest being the "true sedges", with over 2,000 species.

Distribution

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 s or as sedge meadows.

Classification

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 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, noded grasses.
Some well-known sedges include the water chestnut and the papyrus sedge, from which the writing material papyrus was made. This family also includes cotton-grass, spike-rush, sawgrass, nutsedge or nutgrass, white star sedge, and umbrella sedge, also known as umbrella papyrus

Features

Members of this family are characterised by the formation of dauciform roots that are an alteration in root morphology that researchers regard as analogous to cluster roots in Proteaceae, which help uptake of nutrients such as phosphorus from poor soil. Like other members of the order Poales, sedges are mostly wind-pollinated, but there are exceptions. Cyperus niveus and Cyperus sphaerocephalus, both with accordingly more conspicuous flowers, are insect-pollinated.

Evolution

Researchers have identified prominent sedges occurring at least as early as the Eocene epoch. Earlier fossils date to the Late Cretaceous.

Genera

, 95 genera are accepted by Kew's Plants of the World Online.