They rise, sharply scented, from our graveyards. Spreading underground from the "mother plant", they creep along ditches, across meadows and into the cities. We beat them back from our gardens, but they rise again, under cover of more friendly foliage, to snap at the wrists and ankles of the ungloved and inadequately socked. But, this week (17 to 28 May), the brave botanists of the Natural History Museum are asking us to celebrate Be Nice to Nettles Week.
As a regularly stung rambler, I felt the scars of welts-past bridle. "Why should we be nice to nettles?" I asked Gillian Edom, one of the experts who'll be speaking at the museum this week. "What have the nettles ever done for us?" "Apart from providing food, cloth, myths and medicine?" she laughs. "Well, they're a great breeding ground for butterflies."
Edom loves surprising folk with the many marvels of Urtica dioica. "People get angry, upset and frustrated around nettles," she says. "Everybody has a story about being stung. Yet they have a very symbiotic relationship with humans. We go around disturbing the ground, which stimulates growth of the seeds (otherwise they are more likely to grow from rhizomes stretching out beneath the soil). Then we feed the nettles with nitrates and phosphates from sewage and bones. That's why they're so commonly associated with graveyards. I sometimes joke that if they didn't have stings they would be extinct - they are so useful that people would have picked them all!"
As we fight to reduce food miles and rediscover "traditional English cuisine", the common stinging nettle is making a culinary comeback, with celebrity chefs like Hugh Fearnley-Whittingstall inciting us to raid the hedgerows and whip up nettle soups and risottos. For five years, the Northumberland Cheese Company have made a delicious, creamy nettle cheese, speckled with dusky green. Tasting of spinach, high in iron and, currently, a soupçon more chic than rocket, nettle leaves are free and fun. "Until relatively recently, nettles would have featured regularly in the rural diet," says Edom. "We have accounts written by English aristocrats who were shocked, on visiting Ireland during the potato famine, to see the peasants eating what they saw as weeds. In fact, they would probably have eaten nettles anyway, famine or not." Samuel Pepys even records consumption of a "very good" nettle porridge in his diary.
But to eat them, we must first risk the sting which gives the nettle its name, probably derived from the Anglo Saxon noedl meaning needle. Edom explains that "the plant's stinging mechanism is similar to that of the hypodermic needle. Each sting is actually a hollow hair stiffened by silica with a swollen base that contains the venom. The tip of this hair is very brittle and when brushed against, no matter how lightly, it breaks off, exposing a sharp point that penetrates the skin and delivers its stinging payload."
But it's a myth that formic acid causes the burning sensation that demands to be scratched. The solution would have to contain at least five per cent formic acid for that to be the case and in the nettle it only accounts for 1 per cent. "The main chemicals are histamine, acetylcholine and 5-hydroxytryptamine (serotonin)," says Edom. "A fourth ingredient has yet to be identified."
No one in the UK has ever died of a nettle sting, as far as we know. But our nettle is less vicious than the other 500 species around the world. One type in Timor causes symptoms such as lockjaw, which can last for days or weeks. Another from Java lasts for months and has been known to kill some of its victims.
The more tolerable sting of the European nettle means it has long been used as a playground trial of bravery. In Cider with Rosie, Laurie Lee recalls plunging his arm into nettles to impress Rosie Burdock. In fairy tales, such as Hans Christian Anderson's "Wild Swans", a princess must weave nettle coats to turn her 11 brothers from birds back to boys.
"Historically, we find the nettle coming to prominence as a textile in times of war and political trouble when cotton imports are threatened," says Edom. But many of the claims for the widespread possibilities nettle fibre - especially those made by the Germans in the First World War - were propaganda-spun. "It is incredibly difficult to extract the fibre from the stems," she says. "I know. I've tried!"
Nettles have been traditionally used to make tablecloths and sheets in Scotland, although the Scots term "nettlecloth" can also be used to describe all manner of fine fabric. Today, in Tibet and Nepal, nettles are used to make shawls so delicate that they can be pulled through a wedding ring.
Medicinally, the nettle has long been used to treat complaints of all the bodily fluids. Culpeper recommended the use of nettles to "consume the phlegmatic superfluities in the body of man, that the coldness and moisture of winter has left behind" and prescribed the juice of the leaves as a treatment for gangrene and scabies. Native Americans used the fresh leaves to treat aches and pains, while European herbalists treated gout and arthritis with a similar poultice. Edom tells me that although a fresh nettle causes a sting, dried leaves have anti-histamine and anti-asthmatic properties. It's a diuretic, too, and scientists are investigating its use in the treatment of benign prostate hypertrophy.
As my own contribution to Be Nice to Nettles Week, I'm planting a big pot of nettles in my tiny garden. My honeysuckle is infested with aphids and I'm hoping they will help encourage the ladybirds that I need to defeat the pests. Brewed, nettles make brilliant organic plant food; sprayed, they can fight fungus. These aren't their only selling points. The nettle supports more than 40 species of insect including the red admiral, peacock, small tortoiseshell and comma butterflies. Who would have thought that such a spiky, dull-green, cemetery-dwelling plant could provoke such a flurry of life and colour?
Be Nice to Nettles Week 17-28 May. See www.nettles.org.uk or www.nhm.ac.uk for events at Natural History Museum
Remedies and riches
* Nettle stings can help to relieve arthritis by drawing blood to the affected areas.
* Dock leaves, commonly found growing in the vicinity of nettles, really do relieve the pain of a sting - and you could also use the pulp of the nettle itself.
* Nettles leaves are also a great addition to the compost heap. Being rich in nitrogen, they provide fuel for the bacteria that help to break down the more woody material in the heap.
* Insects can also move between the spines without activating the sting.
* In late summer, the huge quantity of seed produced provides a food source for many of our seed-eating birds.
* In Sweden the nettle is sometimes fed to milking cows because it can sometimes help to increase the production of milk.
* Horses are sometimes fed nettle seeds to improve the condition of their coat.