Cultivated parsnips, with their sweet, cream-yellow flesh and aromatic aroma, have been familiar root vegetables, especially during the lean winter months, for millennia. However, evidence for the time and place of the domestication of wild forms of parsnip is difficult to obtain since Roman and Greek writers make no distinction between parsnips and carrots, and parsnips do not preserve well in archaeological deposits.
Parsnips are biennials (they take two years to flower) and reproduce entirely by seed. At the end of the first year, a rosette of strongly scented, rough, hairy leaves forms on the top of the familiar tap root. These roots are usually harvested after the first frost, when some of the storage starches have been converted to sugars. If left in the ground for the next growing season they bolt, producing tall stalks with clusters of small, yellow flowers that eventually form groups of dry, flat, winged fruits. By this stage, the taproot is woody and inedible.
Parsnips are a rich source of sugars, and before the widespread availability of sugar cane and sugar beet they were used as everyday sweeteners. They are still used to make rustic wines. However, the sap of parsnip leaves and stems contains high concentrations of furanocoumarins, toxic chemicals that may produce photodermatitis, i.e., blistering and burning of skin exposed to sunlight.
Wild parsnips are naturally distributed through Eurasia, and readily hybridise with cultivated parsnips. The rapid transformation of wild to cultivated parsnips was demonstrated by James Buckham, Professor of Geology, Botany and Zoology at the Royal Agricultural College, Cirencester, in the mid-nineteenth century. Appointed in 1847, Buckham started to select artificially wild parsnips from root quality. By 1860, he had created the cultivar 'Student', which was eventually marketed by the seed company Messrs. Suttons of Reading. The long, smooth, fine-textured roots with their sweet, mild flavour were immediate winners; by the end of the century 'Student' was one of the most widely planted and consumed parsnips across the English-speaking world. Buckham however lost. In 1863, he was dismissed from his post, and the experimental research garden he had established was obliterated, because of his support for Darwin's evolutionary ideas.
Ironically, cultivated parsnips introduced as crops to North America by English and French colonists in the late-1500s and early-1600s, have escaped from cultivation, reverting to their wild forms. Feral parsnips are now serious weeds of agriculture and waste places in North America.
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