Stinging nettle is a perennial herb originating in Eurasia, but now naturalized over much of the world. Its many documented uses, from as far back as the Bronze Age, led to its seed being carried to numerous regions by settlers, where the plant soon escaped cultivation. The whole stinging nettle plant is valuable — leaves, seeds and roots. Its uses include food, traditional remedies, a fiber source, a dye plant and a rejuvenating spring tonic.
Botanical name: Urtica dioica L.
Common name: stinging nettle
Synonyms: common nettle, nettles, sumidad de ortiga (Spanish)
The Plant: There are two species of nettle recognized in various pharmacopoeia’s as interchangeable — Urtica dioica, or stinging nettle, and Urtica urens,, or dwarf nettle. Dwarf nettle is a two- to three-foot annual with a taproot, while stinging nettle is a tall perennial with creeping rhizomes that send up new plants, often creating thickets of stinging nettle. Urtica dioica, is the species most often offered as the herb in the U.S., although dwarf nettle is sometimes sold in Europe and can occasionally be found mixed in with nettles herb in this country when the plants sold were wild-harvested in Europe.
Stinging nettle herb grows up to six feet in height. It prefers rich, moist soil and is found growing wild in temperate zones around the world on stream banks, disturbed soils and partly shady areas. The stem and leaf of the nettle plant are covered with two types of plant hairs or trichomes — stinging trichomes and glandular trichomes. The stinging trichomes contain an irritant made up of histaminie, acetylcholine and serotonin. When the fresh plant is brushed, the tips of the stinging trichomes break off into the skin, releasing their contents. The burning, stinging, irritating feeling at the site of a nettle sting can last for several hours. For those who have accidentally brushed against nettles and been rewarded with the stings, it’s hard to believe that people have intentionally lashed themselves with brunches of fresh nettle to provoke this irritating skin rash. Using nettles in this way as a counter-irritant, is an age-old remedy called urtication, and was done to stimulate or warm a limb or joint.
nettleWhen the herb is dried, the constituents responsible for the sting are quickly dissipated — although even with their stings neutralized, the trichomes on the leaves and stems can cause skin irritation in the dried herb. These stinging trichomes can be seen in the lab under a microscope. The large hollow hypodermic needle-like structures seen in the photo are the stinging trichomes on a dried nettle leaf. Other non-stinging trichomes cover the leaf.
The parts used of the nettle plant used include the leaf, stripped from the stem after drying, the roots and the seed. Freeze-dried juice and leaf are used when the constituents found in the stinging trichomes are desired in the final product.
Constituents of Note: Chlorogenic acid, while present at low levels, is considered a key marker ingredient in nettles herb. A variety of other constituents, including flavonoids and histamine and other amines, and plant sterols are also present. Nettles leaf also contains a variety of nutrients that vary in quantity depending the age of the plants and where and when they are harvested — vitamin C, beta-carotene, calcium, magnesium, chlorophyll, proteins and dietary fiber have all been reported. Nettles root contains several lignins, tannins and phytosterols.
nettleQuality: Stinging nettle leaf is best harvested when the herb is in full bloom and before it goes to seed, so little or no seed should be present in the dried herb. Nettle leaf should not have any woody or large stems with less than 5% of small, thin stem pieces present. Due to their fibrous nature, clumps of leaves may be present in the herb. Nettle leaf is medium green in color with the upper surface of the leaves a darker green and the underside lighter green as seen in the picture o