Stinging Nettle

Theodore Webster, USDA Agricultural
Research Service, Bugwood.org

In New York there are two very similar subspecies of tall perennial stinging nettles, American (Urtica dioica ssp. gracilis) and European (Urtica dioica ssp. dioica). Both are common, especially in disturbed areas. They are apt to grow near streams, along trails, and are especially common around old farm sites. Since nettles can grow up to 8 feet tall, going through a large patch of nettle can be a daunting prospect.

Formerly all stinging nettles were thought to be introduced European nettles. However many of these plants, especially in natural areas, have been recognized as a native subspecies. Given that European and American nettles are hard to distinguish unless they are in bloom, identifying them both as stinging nettles is sufficient if the objective is merely to avoid being stung.

Identification

Stinging nettles are usually found in dense stands which spread vegetatively by underground stems called rhizomes. Although nettles produce prodigious amounts of seed, their most reliable means of spread is by rhizomes. Rhizome fragments are readily spread by soil disturbances such as plowing, ditch cleaning and construction.

Nettle stems are quite slender, square and grow 6 to 8 feet tall, with occasional thin branches. Leaves are thin, dark green, 2 to 4 inches long, with a tapered tip. The edges of the leaves are toothed and the leaf surface is distinctly veined and rather rough looking. The leaves are opposite along the stem. Long clusters of tiny male or female flowers are produced at the base of each pair of leaves. They are usually light green or tan, and are apt to look rather messy and tangled.

Nettles have both ordinary and stinging hairs on stems, leaf petioles (stem part of a leaf) and undersides of the leaves. Stinging hairs are longer, about 1 millimeter long, and tend to stick out aggressively. Stinging hairs are most abundant on the stems, leaf petioles and undersides of the leaves, especially along the leaf veins.

Where Stinging Nettle is Located

Theodore Webster, USDA Agricultural
Research Service, Bugwood.org

Nettles occur in all parts of New York, but are most common in riparian areas, along stream banks and also in disturbed areas especially farmland. In hot areas, they favor sites in partial shade, but will grow in full sun in moist soils along streams or in ditches.

Why Stinging Nettle is a Problem

A stinging nettle sting can feel like a bee sting: sharp, sudden, and very painful. It's almost an instinct to look for a bee or stinging ant as the culprit rather than the tall straggly plants along a trail or weeds in a garden. Even a small nettle plant only a few inches tall can deliver a nasty sting. People pulling weeds have even been stung through cloth gloves.

Nettles have hollow stinging hairs about 1 millimeter long on their leaves and stems. When a stinging hair is touched, the tip breaks off leaving a microscopic hollow needle which injects a little dose of histamine, acetylcholine, serotonin and formic acid. These cause an immediate painful skin reaction, sometimes with burning, itching or tingling for several hours.

This is an irritant rather than an allergic reaction.

Historical Uses of Nettles

Stinging nettles have a long history of use for food, medicine and fiber. Since cooking deactivates the stings, young nettle leaves make highly nutritious cooked greens. Traditional and alternative medical uses include using the actual stings to counter arthritis pain, and various extracts made from the leaves and roots to treat many conditions. The long stems are a traditional source of fiber to make cloth. Interestingly, although livestock avoid live stinging nettle for obvious reasons, they can eat dried nettles, which rival alfalfa for protein and nutrition levels.