Plantwatch: A vicious, but useful, weed

The mild weather this winter has tricked many plants into growing early. Unfortunately that includes a very aggressive plant – the stinging nettle, one of Britain's most troublesome weeds, which thrives on the copious amounts of nitrogen fertilisers washed off farmlands and gardens.But the plant is most notorious for its vicious stinging hairs. Brushing against these small delicate hairs inflicts pain and a burning sensation that lasts for several hours. Just the slightest touch snaps off the top of a hair, leaving a jagged end that scratches the skin. Like a hypodermic needle, the hairs inject chemicals remarkably like those in our own nervous system – acetylcholine and hydroxytryptamine. Added to this venomous cocktail is histamine, which brings on inflammation and enhances the burning sensation. The folklore remedy for nettle stings is to rub on the leaves of the broad-leaf dock, and there could be something in this because the dock contains a chemical antidote to hydroxytryptamine.For such an unpopular plant, the stinging nettle can be incredibly useful. Young shoots can be used in soups or eaten if cooked like spinach – cooking destroys the sting. Their fibres were used for making cloth and, during the second world war, nettles were collected for a dark green dye for camouflage. The Romans used to beat themselves with nettles to relieve rheumatic pains, and research is now being carried out into using nettles to relieve arthritis.PlantsPaul Simonstheguardian.com &c...
Source: Guardian Unlimited Science - Category: Science Authors: Tags: The Guardian Features Plants Environment Science Source Type: news