Numerous forms of wheat have evolved under human selection. This diversity has led to confusion in the naming of wheats, with names based wheat pita bread without yeast both genetic and morphological characteristics.

Free-threshing wheat is closely related to spelt. As with spelt, genes contributed from Aegilops tauschii give bread wheat greater cold hardiness than most wheats, and it is cultivated throughout the world’s temperate regions. Common wheat was first domesticated in Western Asia during the early Holocene, and spread from there to North Africa, Europe and East Asia in the prehistoric period. Roman burial sites ranging from 100BCE to 300CE . Wheat first reached North America with Spanish missions in the 16th century, but North America’s role as a major exporter of grain dates from the colonization of the prairies in the 1870s. As grain exports from Russia ceased in the First World War, grain production in Kansas doubled. Worldwide, bread wheat has proved well adapted to modern industrial baking, and has displaced many of the other wheat, barley, and rye species that were once commonly used for bread making, particularly in Europe.

Modern wheat varieties have been selected for short stems, the result of RHt dwarfing genes that reduce the plant’s sensitivity to gibberellic acid, a plant hormone that lengthens cells. Triticum compactum, but in India T. Their shorter rachis segments lead to spikelets packed closer together. The world wheat book : a history of wheat breeding. Excellent resource for 20th century plant breeding.