Genetic and Phenotypic Odyssey: Voyage of the Grain Amaranths from the Americas to the Old World

The grain amaranths consist of three species, Amaranthus hypochondriacus L., Amaranthus cruentus L., and Amaranthus caudatus L., which were domesticated in the Americas in pre-historic times. European botanists from the eighteenth through twentieth centuries described grain amaranths observed over a vast region of Asia where they were cultivated for grain and as a potherb, a smaller region in Africa, where they were mostly cultivated as an ornamental and as a potherb, and also in Europe, where they were cultivated as an ornamental and a commercial source of dyes. These botanists recorded that the grain amaranths were under intensive cultivation for grain in two regions of the Indian subcontinent: (1) in the north in the Himalayas and adjoining foothills and plains and (2) in the extreme south surrounding the cities of Coimbatore, Salem, and Madura. So entrenched were the grain amaranths in the culture of the people who cultivated them, botanists at the time presumed that these amaranth species were native to the region. Comparison of the Asian grain amaranths with their American counterparts led twentieth century botanists to conclude that the Asian grain amaranths were, in fact, a subset of their American counterparts and had been introduced into Asia through human contact. Jonathan D. Sauer conducted a fully revised taxonomy of the grain amaranths and concluded that the Asian amaranths were probably introduced from the Americas in the sixteenth century. Others have speculated, on the basis of limited evidence, that the Asian amaranths are among a number of plant species domesticated in the Americas that were introduced to Asia through pre-Columbian contact.