Weed: Urtica dioica. Common names include stinging nettle and tall nettle.
Description: It is dioecious, having separate male and female flowers on the same plant. Stinging nettle gets part of its botanical name dioica from dioecious. Clusters of flowers form at the upper leaf axils. The plant can grow from 2 to 6 feet tall. The stems are hollow and square with ridges. The opposite leaves are lanceolate with rough serrated edges. It could easily be mistaken for a mint plant. Usually there are 4 stipules at the base of each petiole that help when identifying the plant.
The most notable parts of the plant are the hairs on the leaves and stems. Each hair has a bulbous end that breaks when touched, releasing acetylcholine, histamine, 5-hydroxytryptamine, and possibly formic acid (some resources include formic acid and others do not). This mixture causes a stinging sensation that can last up to 12 hours. Photo showing leaves was taken by Tom Dorn, UNL Extension.
Where: In Nebraska, the plant prefers moist sites along streams, open forests, and ditches. It also may be found in disturbed areas such as roadside ditches and old fields.
Propagation: Stinging nettle spreads mainly by underground rhizomes. It can spread by seeds that do not need a dormancy period.
Poisoning: The combination of histamine, acetylcholine, and formic acid causes stinging pain in both humans and grazing animals. Large amounts can cause respiratory distress and an irregular heartbeat. Boiling the plant removes the irritants. Stinging nettle may interfere with prescription medications such as for diabetes and hypertension.
Historical: Stinging nettles include both native and introduced varieties in North America. The introduced variety from Europe has not spread widely in the U.S. Ancient healers would whip or beat paralyzed limbs with stinging nettles, a process called urtication. The ancient Romans supposedly used nettles to increase virility by thrashing the kidneys and lower torso below the navel. For centuries people used a spring tonic made from boiled nettle leaves to treat winter anemia.
What: While many of us think of stinging nettle as nothing more than a real pain, this is a highly acclaimed plant whose benefits cover a wide range of uses including compost, green dye, fiber, hair rinse, liquid feed, oil, fly repellent, waterproofing, herbal medicines, and butterfly and moth food.
Pros: The stems have strong flax-like fibers that have been used for making string, cloth, and paper. The fiber is harvested as the plant begins to die down in early autumn. Native Americans are said to have used it for rope and weaving into cloth. The fiber was used in Germany and Austria during the WWI.
Food: Boiling takes away the sting so that the plant becomes edible. As a tea, cooked leaves are considered a nutritious food that is high in minerals and vitamins. Nettle has many, many proponents for use of it as a food source. Recipes are available online from the University of Wisconsin. As nettle is highly nutritious, there are many recipes available.
A commercial product using nettle is Cornish Yarg cheese. Before being left to mature, this cheese is wrapped in nettle leaves to form an edible rind. The juice of the leaves can be used as a rennet substitute in making cheese. Stinging nettle leaves have been used in pesto, cordials, and herbal tea. Nettle beer is brewed from the young shoots. There are many websites with recipes for making this type of beer.
Healing: According to the Kew Gardens website, in Britain, "traditional methods of treating rheumatism involved deliberately stinging the afflicted area with nettle leaves! While this may seem strange, research has shown that nettle stings have anti-inflammatory properties that disrupt the NF-AAb pathway and inhibit other inflammatory responses." In Weeds of Nebraska and the Great Plains(Stubbendieck et al, 1994), people with rheumatism "allowed themselves to be rubbed by the plants with the belief that the counter-irritant would alleviate their suffering."
Wildlife benefits: Nettles are the food plant for larvae of several species of butterfly moths. In one English community the leaves are fed to pigs to fatten them up, but it is not explained how the pigs are able to find them palatable.
Cons: This weed can cause a severe burning pain when it brushes against bare skin. Its pollen is plentiful and contributes to hay fever.