Classification
More than 30 subspecies of wheat (Triticum) are known. Some are cultivated, and some still grow wild. A wheat species is classified according to the number and makeup of chromosomes and the structure of the head (spike or ear) of the plant. Chromosomes are the carriers of genetic information in the plant cell. The primitive and early cultivated wheats, such as einkorn (T. monococcum), had only 14 chromosomes. They are called diploids. Later types, such as durum (T. durum), emmer (T. dicoccon), and Polish wheats (T. polonicum), have 28 chromosomes and are called tetraploid wheat. The hexaploid wheats—spelt (T. spelta), club (T. compactum), and most of the common bread wheats (T. aestivum)—have 42 chromosomes. Most commercial wheats are either common wheat, used to make bread and flour; durum wheat, a hard wheat used for stock feed and to make pasta such as spaghetti and macaroni; or club wheat, a softer type, low in protein, used for pastry flour.
S 34° 15.592′ E 139° 06.195′