Urtica

A strange name for today's blog entry and one which refers to the subject, the Common (or stinging) Nettle (Urtica dioica).
Anyone who has ever been stung by these misanthropic plants will know how painful it can be. Looking closely at the stem of a nettle, it becomes clear why.

The stinging hairs are concealed among thousands of non-stinging hairs, but are still easily seen, looking like transparent hypodermic needles.

These 'needles' are extremely brittle and when they have stuck into your skin, they break off, leaving tiny fragments in the skin. The sting and the pain is produced by a cocktail of chemicals which are injected at the time. These include Acetylcholine, which attacks the nervous system, Histamine which works on the immune system and triggers an inflammatory response and Serotonin, which is normally to be found in the gastro-intestinal tract and actually has the effect of creating feelings of happiness and well being.

The sting may also include Formic Acid which is also found in the stings of many ant species and has a powerfully painful effect.
Despite all the negatives, Nettles are an essential part of the countryside, providing the food for (sometimes exclusively), many different moth and butterfly species. The best known of these is the Peacock butterfly.