Before cane sugar reached Europe, the humble parsnip served as a sweetener
Parsnips taste sweeter than carrots, and they get sweeter still if left in the ground through winter frosts. That natural sugar made them useful in Europe as a sweetener before cane sugar arrived. The Romans grew them too, though writers of the time did not always keep parsnips and carrots apart.
Pastinaca sativa, formally described by Linnaeus in 1753, is a native of Eurasia and a close relative of carrots and parsley. It lives for two years but is usually harvested after one. In the first season it forms a rosette of hairy, toothed leaves up to 40 centimetres long that smell pungent when crushed, above a long, cream-coloured taproot. Most roots are narrow cones, but processors favour rounder cultivars because they are less likely to snap.
Left alone, the plant sends up a hollow, grooved flowering stem that can top 150 centimetres, carrying loose umbrellas of small yellow flowers up to 20 centimetres wide. Each flower has five inward-curled petals. The seeds that follow are flat, winged and straw to pale brown. By then the stem has turned woody and the root is no longer worth eating.
European settlers carried the parsnip to the Americas, where it escaped and became a common weed across North America. Wild parsnip is not a separate species: it belongs to the same taxon as the garden crop and crosses with it freely. The wild plant also carries a hidden hazard. Every part contains furanocoumarins, compounds that make skin react to sunlight, which can bring on rashes or blisters, and contact with the eyes can be even more serious.
Growers do best with deep soil free of stones, which lets the root grow straight. The crop has its share of enemies, including the carrot fly and assorted viruses and fungi, with canker the most damaging disease. Botanists have described several subspecies and varieties over the years, but most are now regarded simply as variations of a single taxon with 22 chromosomes.
Source: Parsnip
