Manihot is a genus of approximately 100 species of monoecious trees, shrubs, and a few herbs belonging to the spurge family, Euphorbiaceae, in the order Malpighiales. The genus was formally described in 1754 and is native exclusively to the Americas, ranging from the state of Arizona in the southwestern United States south through Central America and South America to Argentina and Uruguay, with its greatest diversity in Brazil.
Plants in the genus are characterised by their milky sap and monoecious habit — bearing separate male and female flowers on the same individual. Many species produce palmately lobed leaves and develop fleshy or tuberous roots. Manihot species also serve as larval food plants for some moth species, including Endoclita sericeus and Hypercompe hambletoni.
By far the most economically significant member is cassava, Manihot esculenta, one of the world's most important food crops. Cassava is cultivated throughout tropical and subtropical regions for its starchy tuberous roots, which serve as a primary caloric staple for over 800 million people — ranking as the third-largest carbohydrate source in the tropics after rice and maize. The plant is prized for its exceptional drought tolerance and ability to thrive on poor soils. However, cassava roots contain cyanogenic glycosides (linamarin and lotaustralin) that require careful preparation — including soaking, fermentation, or thorough cooking — before they are safe to eat. Wild progenitor populations of cassava are centered in west-central Brazil, where the crop was first domesticated as much as 10,000 years ago, before spreading to Africa and Asia via Portuguese and Spanish traders during the 16th century.
Etymology
The generic name Manihot — along with the common name "manioc" — derives from the Guarani (Tupi) word mandioca or manioca, the Indigenous name for the plant in its native South America. The common name "cassava" entered English via 16th-century French or Portuguese cassave, itself from the Taíno word caçabi.
Distribution
Manihot is native to the Americas, spanning from Arizona in the southwestern United States southward through Mexico, Central America, and South America to Argentina and Uruguay, with its centre of diversity in Brazil. Cassava (M. esculenta) has been introduced across tropical and subtropical regions worldwide and is now cultivated extensively in sub-Saharan Africa, South and Southeast Asia, and the Pacific.
Ecology
Manihot species are adapted to warm, seasonally dry environments and are notable for their drought tolerance and capacity to grow on nutrient-poor soils. Cassava (M. esculenta) grows within 30° of the equator, tolerating rainfall from as little as 50 mm to 5,000 mm per year and elevations up to 2,000 m. Several Manihot species host larvae of specialist moths, including Endoclita sericeus and Hypercompe hambletoni.
Cultivation
Cassava (M. esculenta), the primary cultivated species, is propagated vegetatively by planting stem cuttings of approximately 15 cm before the wet season. Optimal growth occurs at mean annual temperatures of 20–29 °C, though the plant tolerates a range of 12–40 °C. Annual precipitation between 1,000 and 2,500 mm is optimal; cassava is notably tolerant of drought and poor soils, making it a critical crop for subsistence farmers in tropical regions.
History
Cassava (M. esculenta) was first domesticated in west-central Brazil from its wild progenitor M. esculenta subsp. flabellifolia, with archaeological evidence suggesting domestication up to 10,000 years ago. By 4600 BC, cassava pollen appears in Gulf of Mexico lowlands; the oldest direct cultivation evidence comes from a 1,400-year-old Maya site in El Salvador. Portuguese traders introduced cassava to Africa from Brazil in the 16th century, and Spanish and Portuguese traders spread it to Asia through the Columbian Exchange, planting it in colonies in Goa, Malacca, eastern Indonesia, Timor, and the Philippines.
Cultural Uses
Cassava roots are processed into a wide range of foods worldwide: tapioca starch, farofa and farinha (Brazil), gari and fufu (West Africa), and various breads and flours across South America and the Caribbean. Cassava is the third-largest source of carbohydrates in the tropics and is depended upon by over 800 million people as a primary food staple. The leaves are consumed as a vegetable in some regions. Bitter varieties require extensive processing — soaking, fermentation, pressing, and cooking — to remove toxic cyanogenic glycosides before consumption.
