Triticum, commonly known as wheat, is a genus of annual grasses in the family Poaceae and tribe Triticeae. The genus was established by Linnaeus in Species Plantarum in 1753, and its type species is the bread wheat, Triticum aestivum. Plants are upright annuals with jointed, typically hollow straw-like stems and narrow flat leaves. The inflorescence is a terminal spike bearing twenty to a hundred small flowers grouped into spikelets at each node of the rachis; pollination is by wind, though the flowers are more than 99 percent self-pollinated.
The genus is native to a broad arc of the Mediterranean, southwest Asia, central Asia, northwest India, and Ethiopia, with the Fertile Crescent recognised as the principal centre of origin and domestication. From this homeland wheat has been carried to every inhabited continent, and is now cultivated in temperate, Mediterranean, and seasonally dry tropical regions worldwide. In modern taxonomic treatments by Kew's Plants of the World Online, the genus comprises a small number of accepted species — Triticum aestivum, T. monococcum, T. timopheevii, T. turgidum, T. urartu, and the hybrid T. × zhukovskyi — although broader treatments recognise roughly twenty taxa across diploid, tetraploid, and hexaploid ploidy levels. The polyploid species arose through ancient hybridisation events between earlier wheats and goatgrasses of the closely allied genus Aegilops.
Wheat is the most widely grown food crop on Earth: in 2024 it occupied roughly 219.5 million hectares of cropland, more than any other staple. The grain provides the basic carbohydrate of bread, pasta, semolina, noodles, bulgur, couscous, and beer across most of Eurasia, North Africa, and the Americas, and supports very large livestock-feed industries in Europe and elsewhere. Cultivated forms include hexaploid bread wheat (T. aestivum) for breads and general flour use, tetraploid durum (T. durum, treated within T. turgidum) for pasta and semolina, hexaploid spelt, and the ancient diploid einkorn and tetraploid emmer that were among the founder crops of Neolithic agriculture. Beyond the grain, wheat straw is used as livestock bedding, thatching, paper fibre, and garden mulch.
Etymology
The genus name Triticum is Latin and was applied by Linnaeus directly to the cereal grain known to the Romans as wheat. The name therefore predates modern botanical nomenclature and was adopted unchanged as the formal generic epithet when the genus was published in Species Plantarum in 1753.
Distribution
The natural range of Triticum runs from the Mediterranean basin eastward through the Fertile Crescent and the Caucasus into central Asia, with outliers into northwest India and Ethiopia. POWO records native occurrences in Afghanistan, Albania, Bulgaria, Egypt, Greece, India, Iran, Iraq, Kazakhstan, and many other countries of southwest Asia and northeast Africa. Cultivated forms are now grown on every inhabited continent: major producers include China, India, the United States, Russia, France, Pakistan, Germany, Canada, and Turkey, and the genus is naturalised or established as a casual escape in many additional countries across the Americas, Europe, sub-Saharan Africa, and Oceania.
History
Hunter-gatherers in the Fertile Crescent were harvesting wild wheats as early as 21,000 BC, but wheat remained a minor dietary component until the Neolithic. Einkorn (T. monococcum) was domesticated around 8800 BC in southeastern Anatolia, where genetic selection for non-shattering ears made the new crop dependent on humans for seed dispersal. Emmer (T. turgidum) followed a similar trajectory, with the earliest secure archaeological evidence from Çayönü at roughly 8300–7600 BC; both species are among the Neolithic "founder crops." Hexaploid bread wheat is documented by DNA from Çatalhöyük around 6400–6200 BC, the product of further hybridisation events with Aegilops goatgrasses. Wheat then spread rapidly across Eurasia: to Cyprus by 8600 BC, Greece by 6500 BC, Egypt after 6000 BC, Britain and Scandinavia by 4000 BC, India by 3500 BC, and China's Yellow River by 2600 BC. In the twentieth century Japan's Norin 10 dwarfing germplasm and Norman Borlaug's Green Revolution dwarf varieties dramatically lifted yields and reshaped global agriculture.
Cultivation
Wheat is grown as a temperate-to-Mediterranean annual on a vast range of soils, but does best in deep loams rich in organic matter. Plants need full sun and dislike shade, and tolerate light, medium, or heavy textures and a neutral-to-alkaline pH. Roughly 30–38 cm of rainfall during the growing season is required for a reliable crop. Winter wheats need a dormancy period at temperatures below about 4 °C to vernalise and head out the following spring, while spring wheats are sown after the last frost and tolerate growing-season temperatures from roughly 4 to 35 °C.
Propagation
Wheat is propagated by direct sowing of the grain into prepared soil; depending on cultivar group, seed is sown either in autumn (winter wheat) or in spring (spring wheat). The crop is overwhelmingly self-pollinated (more than 99 percent), which makes pure-line cultivar maintenance straightforward in commercial seed production.
Cultural uses
Wheat is the most widely grown food crop on Earth, occupying about 219.5 million hectares in 2024 — more land than any other staple. The grain is primarily ground into flour for bread, pasta, semolina, noodles, couscous, and baked goods, and is also used for beer and other beverages, breakfast cereals, and sprouted-grain foods. Wheat is also a major energy feedstuff for livestock, with starch making up roughly 70 percent of the grain's dry matter; in the European Union nearly half of wheat production goes to animal feeding. Wheat straw has long-standing utility as fuel biomass, thatching, garden mulch, and the fibre base of papers, while seed starch is used in laundering and textile sizing.
Taxonomy notes
Triticum L. was published in Species Plantarum (1753) and remains one of the foundational Linnaean genera in Poaceae. Plants of the World Online currently accepts only six taxa — T. aestivum, T. monococcum, T. timopheevii, T. turgidum, T. urartu, and the hybrid T. × zhukovskyi — and treats names such as durum wheat and spelt as infraspecific taxa within T. turgidum or T. aestivum. Broader treatments, including those reflected in GBIF aggregations, recognise approximately twenty species across diploid, tetraploid, and hexaploid ploidy levels. The polyploid species arose through ancient hybridisations between diploid wheats and goatgrasses of the closely allied genus Aegilops, and that same wild gene pool continues to be tapped for disease-resistance breeding. POWO lists eight generic synonyms, including Spelta Wolf and Frumentum E.H.L.Krause.
Conservation
No species of Triticum is currently treated as globally threatened by major conservation databases; the genus is, by contrast, one of the most abundantly cultivated plants on Earth. The relevant conservation question is in situ preservation of wild relatives — particularly wild emmer (T. turgidum subsp. dicoccoides), T. urartu, and Aegilops goatgrasses — whose populations across the Fertile Crescent remain important reservoirs of disease- and stress-resistance genes for crop improvement.
