Footnote

a An ancient cultivated wheat was called “einkorn” (triticum monococcum). Cytological (cell) examination reveals that it is a diploid plant. Each plant cell contains seven pairs of chromosomes. Another ancient wheat was tetraploid, having 14 pairs of chromosomes. This wheat, called “emmer,” was the wheat of Egypt until after the conquest by Alexander the Great in the fourth century B.C.E., when it was replaced by a new variety of bread wheat.