Watercress is one of the few genuinely wild foods to be cultivated with virtually no modifications . . .
As the name suggests, this peppery plant grows along streams and rivers. It is abundant across the country and although today it tends to be used just as a garnish or to perk up a boring green salad, for years it was an important vegetable thanks to its high Vitamin C and anti-oxidant properties.
Watercress is also unusual in being a wild plant that has been cultivated without refinement. Carrots, wheat and apples may all have wild forebears, but the versions we buy in the shops are virtually unrecognisable when placed next to their ancestors. But the supermarket watercress is identical to that growing in local waterways. Since at least the 18th century it was first ‘ranched’ and then cultivated along Hampshire chalk streams, with trainloads of pallets sent up to London every morning.
It can grow in almost any waterway, but the best comes from reasonably fast-flowing streams with no livestock access. This is because it can potentially harbour a parasite, the liver fluke, which has a lifecycle which revolves around moving from a mammal to a water snail. This then lays its eggs on watercress which is eaten by another mammal. Sheep are the prime hosts, but cattle can also be vectors – and although the parasite is easily killed by cooking, humans can also become part of the cycle.
Whilst nothing beats a wild harvest, if you are impatient or lack a local source, this herb/vegetable is remarkably easy to grow – even if you lack running water. The simplest and cheapest method is to buy one of those bunches bundled up in a rubber band from a market stall. Put a few stalks in a glass of water on a window sill and when the thin white roots begin to snake down, transplant to damp soil. Obviously this needs to be kept moist, but it doesn’t need to be a quagmire and if you keep it damp, the cress is very fast-growing.
As well as making a delicious addition to any bowl of lettuce, watercress is superb pureed in Greek yoghurt as a horseradish-style relish for red meats or oily fish and it also makes a great soup (make a leek and potato base and at the last minute stir in a huge fistful of green leaves).