How Does A Nettle Sting?

There are several species of nettle, not all of which have stinging hairs.
Most people, however, have suffered a nettle-sting at one time or another;
And of those nettles that do sting, the common nettle and the Roman Nettle is the best known. The latter has the most painful sting of all nettles.

The stinging action of a nettle is very similar to the stinging cells in the tentacles of the sea-anemone. It has a delicate, trigger-like coil in a cell, its sharp point being released on the slightest touch. The nettle-sting is developed from a single cell with the walls of the hair solidified, a small knob protects the fine point until touched, when it breaks and allows the trigger to penetrate the skin. It is an acrid juice which causes irritation and, sometimes, inflammation of the skin.
If one is careful, however, to grasp the nettle in such a way that the hairs are pressed to the stem, they cannot pierce the skin, and the nettle can be plucked painlessly.
In many countries, boiled nettles have a special food value for pigs and poultry. The roots boiled in alum produce a yellow dye, and the leaves and stalks give a green dye. The "ramie" (fibres) of different species of nettle are used to make lace, cloth, rope and yarn.