Cyperus esculentus (also called chufa, tiger nut, atadwe, yellow nutsedge, earth almond, and in Chishona, pfende) is a species of plant in the sedge family widespread across much of the world. It is found in most of the Eastern Hemisphere, including Southern Europe, Africa and Madagascar, as well as the Middle East and the Indian subcontinent. C. esculentus is cultivated for its edible tubers, called earth almonds or tiger nuts (due to the stripes on their tubers and their hard shell), as a snack food and for the preparation of horchata de chufa, a sweet, milk-like beverage.

Cyperus esculentus can be found wild, as a weed, or as a crop. It is an invasive species outside its native range, and is readily transported accidentally to become invasive. In many countries, C. esculentus is considered a weed. It is often found in wet soils such as rice paddies and peanut farms as well as well-irrigated lawns and golf courses during warm weather.

Cyperus esculentus is an annual or perennial plant, growing to 90 centimetres (3 feet) tall, with solitary stems growing from a tuber. The plant is reproduced by seeds, creeping rhizomes, and tubers. Due to its clonal nature, C. esculentus can take advantage of soil disturbances caused by anthropogenic or natural forces. The stems are triangular in section and bear slender leaves 3–10 millimetres (1⁄8–3⁄8 inch) wide. The spikelets of the plant are distinctive, with a cluster of flat, oval seeds surrounded by four hanging, leaf-like bracts positioned 90 degrees from each other. They are 5 to 30 mm (1⁄4 to 1+1⁄8 in) long and linear to narrowly elliptic with pointed tips and 8 to 35 florets. The color varies from straw-colored to gold-brown. They can produce up to 2420 seeds per plant. The plant foliage is very tough and fibrous and is often mistaken for a grass. The roots are an extensive and complex system of fine, fibrous roots and scaly rhizomes with small, hard, spherical tubers and basal bulbs attached.

The tubers are 0.3–2.5 cm (1⁄8–1 in) in diameter and the colors vary between yellow, brown, and black. One plant can produce several hundred to several thousand tubers during a single growing season. With cool temperatures, the foliage, roots, rhizomes, and basal bulbs die, but the tubers survive and resprout the following spring when soil temperatures remain above 6 °C (43 °F). They can resprout up to several years later. When the tubers germinate, many rhizomes are initiated and end in a basal bulb near the soil surface. These basal bulbs initiate the stems and leaves above ground, and fibrous roots underground. C. esculentus is wind pollinated and requires cross pollination as it is self–incompatible.

Cyperus esculentus is a highly invasive species in Oceania, Mexico, some regions of the United States (where it is native), and the Caribbean, mainly by seed dispersion. It is readily transported internationally, and is adaptable to re-establish in varied climate and soil environments. In Japan, it is an exotic clonal weed favorable to establish in wet habitats. Cyperus esculentus serves as a larval host for Euphyes vestris (dun skipper) and Diploschizia impigritella (yellow nut-sedge moth) in North America. Cyperus esculentus likely reached the New World through ocean currents before the Holocene.

Cyperus esculentus is cultivated in Egypt, Spain, Nigeria, the United States, Guatemala, Mexico, Chile, Brazil, Lebanon, Syria, Jordan, Saudi Arabia, Oman, Iran, Iraq, Pakistan, India, Yemen, Morocco, Ivory Coast, Sudan, South Sudan, Gambia, Guinea Bissau, Ghana, Niger, Burkina Faso, Togo, Benin, Cameroon, and Mali, where they are used primarily as animal feed or as a side dish, but in Hispanic countries they are used mainly to make horchata, a sweet, milk-like beverage.

Cyperus esculentus cultivation requires a mild climate. Low temperature, shade, and light intensity can inhibit flowering. Tuber initiation is inhibited by high levels of nitrogen, long photoperiods, and high levels of gibberellic acid. Flower initiation occurs under photoperiods of 12 to 14 hours per day.

Tubers can develop in soil depths around 30 cm, but most occur in the top or upper part. They tolerate many adverse soil conditions including periods of drought and flooding and survive soil temperatures around −5 °C (23 °F). They grow best on sandy, moist soils at a pH between 5.0 – 7.5. The densest populations of C. esculentus are often found in low-lying wetlands. They do not tolerate salinity.