Cyperus

Cyperus is a large genus of about 600 species of sedges, distributed throughout all continents in both tropical and temperate regions. They are annual or perennial plants, mostly aquatic and growing in still or slow-moving water up to 0.5 m deep. The species vary greatly in size, with small species only 5 cm tall, while others can reach 5 m in height. Common names include papyrus sedges, flatsedges, nutsedges, umbrella-sedges and "galingales"

The stems are circular in cross-section in some, triangular in others, usually leafless for most of their length, with the slender grass-like leaves at the base of the plant, and in a whorl at the apex of the flowering stems. The flowers are greenish, and wind pollinated; they are produced in clusters among the apical leaves. The seed is a small nutlet.

Ecology

Cyperus species are used as food plants by the larvae of some Lepidoptera species, including Batrachedra cuniculata. The seeds and tubers are an important food for many small birds and mammals.

Cyperus microcristatus and C. multifolius are possibly extinct; the former was only found once, in 1995, and the latter has not been seen in the last 200 years. The "true" papyrus sedge of Ancient Egypt, C. papyrus ssp. hadidii, is also very rare today due to draining of its wetland habitat; feared extinct in the mid-20th century, it is still found at a few sites in the Wadi El Natrun region and northern Sudan.

Some tuber-bearing species on the other hand, most significantly the Purple Nutsedge (C. rotundus), are considered invasive weeds.

Use by humans

Papyrus Sedge (C. papyrus) of Africa was of major historical importance in providing papyrus. C. giganteus, locally known as cañita, is used by the Yokot'an Maya of Tabasco, Mexico, for weaving petates (sleeping mats) and sombreros. C. textilis and C. pangorei are traditionally used to produce the typical mats of Palakkad in India, and the famous makaloa mats of Niihau were made from C. laevigatus.

The Chufa Flatsedge (C. esculentus) has edible tubers and is grown commercially for these; they are eaten as vegetables, made into sweets, or used to produce the famous horchata of the Valencia region. Several other species - e.g. Australian Bush Onion (C. bulbosus) - are eaten to a smaller extent. The Northern Paiutes were considered to be so fond of Cyperus tubers that their native name was tövusi-dökadö ("nutsedge tuber eaters").

Most species are of little economic value. Some are grown as ornamental or pot plants, namely the Umbrella Papyrus (C. alternifolius ), the Dwarf Umbrella-sedge (C. albostriatus, formerly called C. diffusus), and related species. There is increasing interest in the larger, fast-growing species as crops for paper and biofuel production.

Some Cyperus are used in folk medicine. Roots of Near East species were a component of kyphi, a medical incense of Ancient Egypt. Purple Nutsedge (C. rotundus) tubers are used in Kampō. An unspecified Cyperus is mentioned as an abortifacient in the 11th-century poem De viribus herbarum.