What makes nettles sting

A. Stinging nettles, Urtica dioica, contain an acid, which causes the sting we feel when touching them. Specifically the sting is delivered by the stiff, sharp hairs that cover the stem and under side of the nettle's leaves. These spines have a hollow centre that is connected to a supply of formic acid.

Q. What does 'nettle' mean

A. There are a couple of probable explanations for the origin of the word nettle. It may be derived from the Anglo Saxon word 'needle', which describes the sharp prick that the plant delivers.

Alternatively it may be related to one of the plants earliest known uses, as ropes for fishing nets during the Bronze Age in Scotland and Scandinavia.

Q. Didn't the ropes sting the fisherman's hands

A. No, because drying the nettle fibres, as well as cooking them, neutralises the plant's sting and it has had various practical and culinary uses. The fibres were spun into cloth and even used as fabric for sheets and tablecloths.

Q. What makes dock leaves an effective antidote

A. The dock leaf, Rumex crispus, which often grows conveniently close by to stinging nettles, contains an alkali that neutralises the nettles sting and calms the sting.

Q. And so finding a dock leaf is the only solution

A. There is an old saying 'grasp the nettle' that suggests taking hold of the plant firmly, rather than brushing against it, prevents it from stinging. But it's probably a good idea to pin point a good supply of dock leaves before attempting to test this, just in case.

Q. What about using dock leaves for other acidic stings, like bee stings

A. Other alkaline substances, such as soap or bicarbonate of soda will probably be more effective. Wasp stings are alkaline and so dock leaves are useless against them. Instead opt for an acid such as vinegar.

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by Lisa Cardy