- Name also: Common Nettle, Greater Nettle
- Family: Nettle Family – Urticaceae
- Growing form: Perennial herb. Rhizomatous. Forms dense stands.
- Height: 30–150 cm (12–60 in.). Stem usually unbranched, 4-edged, with stinging hairs.
- Flower: Plant dioecious (staminate and pistillate flowers on different plants), flowers very small. Staminate flower: tepals 4, like sepals, greyish yellow. Stamens 4, anthers yellow. Pistillate flower: tepals 4, like sepals, in different-sized pairs, greyish green, hairy. A single carpel, stigma brush-like. Inflorescence catkin-like, 4–8 cm (1.6–3.2 in.) long, longer than leaf-stalks.
- Leaves: Opposite, stalked, stipulate. Stalk with straight, stinging hairs. Blade ovate–narrowly ovate, with cordate or round base, long-tipped, serrated, underside with stinging hairs (occasionally lacking stinging heirs), dark green. Blade at least twice as long as broad, stalk at most half length of blade.
- Fruit: Elliptic, flat, dull, yellowish brown, 1–1.5 mm (0.04–0.06 in.) long, achene protected by tepals.
- Habitat: Yards, gardens, walls, roadsides, banks, pastures, fields, waste ground, logging clearings, shore and stream-side broad-leaved forests, rich mixed swamps.
- Flowering time: July–September.
Stinging nettle can make a real nuisance of itself in vegetable gardens, but it is also one of Finland’s most diverse and useful plants. The young shoots are tasty and extremely healthy in soups, stews and pancakes. It has also carved out a reputation as a useful medicinal plant in many forms: as a tea, tincture, a processed mould, just as it is, or even as a whisk. Its fibre can be used the same way as flax: it is probably the oldest fibre plant known to man and was used in the Stone Age to make nets, and later also clothes. Nettles that grow as weeds can be used to provide excellent green manure for vegetables and flowers.
Even the way that the plant stings can be understood in a different way when one understands what an ingenious system the structure of the stinging hairs is. The hair’s knob-like tip breaks off at the slightest touch and the sharp-edged surface pierces the skin like a hypodermic syringe. The hollow hair squirts liquid from its bottle-like base and its acids irritate and burn the skin. In this way stinging nettle protects itself from being eaten, and large grazers leave it in peace. It is however defenceless against the small jaws of the grubs of small tortoiseshell, peacock, map and red admiral butterflies, which use the stinging hairs to protect themselves. People can use gloves to avoid being stung.
Stinging nettle is generally quite common in all of Finland. The more common subspecies ssp. dioica is only native to the coastal region of southern Finland but it has travelled to the outskirts of inhabited areas almost everywhere. The narrow-leaved subspecies ssp. sondenii, which grows in northern and inland Finland in broad-leaved forests, has almost no sting at all. Its close relative annual nettle (U. urens) is associated with old cultural influence and has become rarer in Finland. Its stem is often branching and the leaf-stalk is relatively long, about 2/3 the length of the blade.