Cyperaceae species are widely distributed with the centers of diversity for the group occurring in tropicalAsia 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.
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 (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.[8][9] This difference leads to the mnemonic "sedges have edges" in order to tell them apart from generally round rushes or hollow, nodded grasses.[10][11]
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, which help uptake of nutrients such as phosphorus from poor soil.[12] 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.[13]
Evolution
This section needs expansion. You can help by adding to it. (February 2024)
Researchers have identified prominent sedges occurring at least as early as the Eocene epoch.[14] Earlier fossils date to the Late Cretaceous.[15]
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Shribbs, John (2021). "Sedges in our wetlands". Petaluma Wetlands Alliance. Retrieved 21 February 2024. Some of the first prominant 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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