The bread wheat (Triticum aestivum or T. vulgare) is a very important grain species. The origins of the modern bread wheat are somewhat uncertain, because this species occurs in many hybrid varieties which have been selectively bred over time by complex, unrecorded hybridizations of various species of Triticum. Some botanists believe that the major progenitor species was an ancient cultivated wheat known as emmer (T. dicoccum) which was grown in the Middle East at least 5,000 years ago. Other ancient wheats which have also contributed to the genetic make-up of the modern bread wheat include einkorn (T. monococcum) from southwestern Asia and spelt (T. spelta) and durum (T. durum) from the Mediterranean region.
The numerous varieties of wheat have been bred for various purposes and climatic regimes. The flowering heads of wheats can have long awns as in the so-called "bearded" wheats, or they can be awnless. Wheat can be sown in the spring or in the previous autumn, known as winter wheat. Winter wheat generally has larger yields than spring wheat because it has a longer growing season. The so-called "soft" wheats are mostly used for baking breads and pastries, while the "hard" or durham wheats are used to prepare pastas and other types of noodles.
Wheat is rarely grown in subtropical or tropical climates because it is too susceptible to fungal diseases under warm and humid conditions. The best climatic regime for growing wheat involves a temperate climate with soil moisture available during the spring and summer while the plants are actively growing, and drier conditions later on while the seeds are ripening and when the crop is being harvested.
Certain landscapes of the temperate zones that used to support natural prairies and steppes are now the best regions for the cultivation of wheat. These include the mixed-grass and short-grass prairies of North America and similar zones in the pampas of South America, the steppes of western Russia and Ukraine, parts of central China and Australia, and elsewhere. Winter wheat tends to be the favored type grown in places where the environmental regime is more moderate, while spring wheats are sown under more extreme climatic conditions.
Wheat grains are manufactured into various edible products. Most important is flour, finely milled wheat, which is mostly used to bake breads, sweetened cakes, and pastries, and also for manufacturing into pastas and noodles. Wheat is also used to manufacture breakfast cereals, such as puffed wheat, shredded wheat, and fiber-rich bran flakes. Wheat grains are fermented in a mash to produce beer and other alcoholic beverages and also industrial alcohol. Wheat straw and hay are sometimes
used as fodder for animals or as stuffing, although the latter use is now uncommon because so many synthetic materials are available for this purpose.