By James Duncan
Learning & Engagement Officer
There are almost certainly very few of us who haven't had an interaction with the familiar and hugely abundant Common 'Stinging' Nettle (Urtica dioica). In fact, man's relationship with the Common Nettle has always been rather conflicted, both loved and reviled in equal measure. It's doubtful there's a more familiar sensory introduction to nature than that of a childhood nettle sting - something that also stops many a browsing mammal in its tracks. The Common Nettle is one of the world's most widely distributed plants, a hardy perennial that bears its male and female flowers on separate plants - its scientific name of dioica translates from the Greek for 'two houses.' Nettles tend to survive where many other plants are chewed to the ground, aided by their sheer adaptability in colonising new habitat. Aside from acidic soils, they thrive on disturbed land, particularly where the concentration of unused nitrates and phosphates is high. Their association with human habitation is remarkably strong and they may often denote the location of former human dwellings in time gone by.
The other part of the name, Urtica, refers to the rather unfavourable sensation that may well punctuate your country walk. The Nettle's urticating hairs, a defensive mechanism shared by many caterpillars, tend to cause symptoms of tingling, inflammation and burning, but just how are the stings produced? Each 'hair' or trichome is essentially a lengthy, brittle tube connected to a swollen sac of irritant fluid. They're smothered all over the stems and leaves and every tube has walls stiffened with silica, making them as delicate as a sliver of paper-thin glass. Brush against them and the tip snaps off, injecting a plethora of unpleasantness into your skin like a tiny hypodermic needle. This complex venomous cocktail contains neurotransmitters such as histamine, serotonin and acetylcholine and acids such as formic, tartaric and oxalic, but it's still not fully understood just how this elaborate brew functions to make a sting so prolonged. In a twist of irony, nettle's have frequently been used as a 'counterirritant' as they have a marvellous ability to reduce the prominence of existing pains.
Common Nettle © James Duncan
Despite the Common Nettle's reputation for irritation, it's proved to be an incredibly useful resource for centuries. When not being used by medieval monks to flagellate (lash) their bare backs, it's been utilised for the creation of textiles and dyes prior to the widespread introduction of flax and of course, for food and drink. Once soaked or boiled, the stinging chemicals are nullified and its richness in vitamins has helped cement its use as both a vegetable and ingredient of tea. Demonstrating its extensive medicinal properties, nettles were readily harvested to provide chlorophyll for medicine during the Second World War and were strongly believed to assist in the treatment of rheumatism. The benefits to wildlife are far more wide-ranging and unaffected by their sting, insects and birds find them ideal for both feeding and breeding. Their density and longevity have enabled many insects to develop a life cycle totally dependant on the Common Nettle. The larvae of the Red Admiral, Peacock, Small Tortoiseshell and Comma all feast upon the nutritious leaves, along with a myriad of magnificent moths. Predatory beetles, flies and spiders relish them as superb hunting habitat. Froghopper larvae, aphids and psyllids all tap the nettle's rich sap-carrying vessels whilst plant-bugs, leafhoppers and thrips suck the juices from individual leaf cells. In fact, no part of the nettle is immune to attack and it truly is a fascinating 'micro-world' in its own right.