Carrot
Daucus carota is a variable, widespread species naturally distributed from the Atlantic coast of Britain and Ireland through Europe and the Mediterranean to Central Asia. It is recognisable by its highly divided, carrot-scented, fern-like leaves and clusters of tiny, white flowers, arranged in parasols, arising from a nest of finely divided bracts. Underground, wild carrot has a small, tough, highly branched, white taproot. In contrast, cultivated carrots have swollen, unbranched taproots in a rainbow of colours: purple, yellow, red, orange, black.
There are two classes of pigments in carrots: water-soluble, purple anthrocyanins and oil-soluble carotenes. Anthrocyanins are powerful antioxidants; carotenes are essential sources of vitamin A. Without sufficient vitamin A we are likely to suffer visual problems such as night blindness. Purple carrots are rich in carotenes but their colours are masked by the anthrocyanins; when boiled purple carrots turn brown. In contrast, xanthophyll-rich, yellow carrots retain their colour when cooked. In addition to colour, other differences among the multitude of carrot types include the shape, size, sweetness and bitterness.
Classical writers were aware of the medicinal and culinary possibilities of carrots but did not clearly distinguish them from parsnips. Today, there is little chance of confusing bright orange carrots with dirty-yellow parsnips. Despite the confusion, classical authors made clear distinctions between taproots from cultivated (manured) and wild plants; the former made good food, whilst the latter were preferred as medicine.
Historical and genetic data indicate domesticated carrots originated in Central Asia. In the early twentieth century, the Soviet geneticist Nicolai Vavilov was emphatic: in Central Asia the 'wild carrots … practically invited themselves to be cultivated'. Modern carrots were selected from wild carrots in the east of the species' range. Their ubiquity across Europe is due to the spread of cultivated carrots not separate domestication events wherever wild carrots were found in Europe. During the tenth and eleventh centuries cultivated carrot spread into Asia Minor and the Iberian Peninsula. In the fourteenth century, the cultivated carrot spread through northwest Europe and finally entered Britain in the fifteenth century.
During the seventeenth century, the kaleidoscope of carrot colours in Western Europe was gradually reduced to one and European carrots became stereotypically orange. The origin of the orange mutant has provoked extensive discussion. Detailed investigation of genetic diversity across many different forms of wild and cultivated yellow, purple and orange carrots has concluded orange carrots were selected from yellow, cultivated carrots.
Further reading
Iorizzo M et al. 2013. Genetic structure and domestication of carrot (Daucus carota subsp. sativus) (Apiaceae). American Journal of Botany 100: 930-938.
Stolarczyk J and Janick J 2011. Carrot: history and iconography. Chronica Horticulturae 51: 13-18.
Zohary D et al. 2013. Domestication of plants in the Old World. Oxford University Press.
Stephen Harris