Nettles have small greenish flowers in slender drooping clusters that form from the upper leaf axils. Stinging Nettle is a native erect perennial growing to 6 feet high with a stem in this subspecies having some well-spaced stinging hairs and either more numerous non-stinging short whitish rough surface hair or stinging hairs with only a minor amount of surface hair. Stems are ridged and green with some reddish tints.
Leaves are opposite, stalked, lance like with coarse teeth and a sharp point. The underside of the leaf of this subspecies has stinging hairs, the upper side is usually smooth or may have soft hair but usually no stinging hair.
The inflorescence is a branched cluster, containing many small flowers, that hangs from the upper leaf axils. The clusters have a creamy color before flower opening.
The flowers are separate by sex. Each cluster however, has either male flowers (staminate) or female flowers (pistillate). In this species they can be on the same plant. The male flowers have 4 distinct tepals (petal and sepal combined function) and 4 stamens and a cup-like sterile vestigial pistil. The female flowers also have 4 distinct tepals but two are inner and larger than the outer two. There is no style on the pistil but the stigma is tufted.
Seed: A single deltoid to ovoid dry seed, less than 2 mm long, is produced and is enclosed by the inner two tepals until ready and then falls to the ground after the first frost or is released by the wind.
Habitat: This species of Urtica is perennial, growing from rhizomes which allows it to form colonies of plants. Stinging Nettle grows in a variety of soils, in disturbed areas, roadsides, floodplains and open woods. It adapts to partial sun and while preferring somewhat moist soils it tolerates some dryness. At Eloise Butler you can find it on the marsh path and nearby is the Canadian Wood Nettle which has alternative leaves and a different looking flower cluster.
Names: The genus name Urtica is from the Latin "uro" meaning "I burn" and refers to the burning sensations of the stinging hair. The species name, dioica, meaning "of two houses" refers to the plant usually having male and female flowers on separate plants. However, this species can have the flowers in separate clusters on the same plant. The common name “Nettle” may be from the Anglo-Saxon and Dutch word “Netel”, that work being derived from “Noedl”, a needle. There is also speculation that it comes from much older words that refer to the ability of the fibers to be sewn (see section below the photos).
The author name for the species plant classification, 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. The author names for the subspecies classification are: First to classify was ‘Aiton’ which refers to William Aiton (1731-1793), Scottish botanist, who succeeded Phillip Miller as superintendent of the Chelsea Physic Garden and then became director of Kew Gardens, where he published Hortus Kewensis, the Garden’s catalogue of plants. His work was amended by ‘Selender’ refers to Nils Sten Edvard Selander (1891 - 1957) Swedish botanist and poet. A man of many interests, he is best known in the field of literature, but he was also chairman of the Swedish Society for Nature Conservation Union, member of the Swedish Academy, and in botany he has the latest accepted classification of several plants including the three subspecies of Urtica dioica.
Comparison: The other stinging nettle found locally is the Wood Nettle, Laportea canadensis, which is shorter, has more ovate leaves and the flower clusters are held more erect near the top of the plant. See comparative illustration below. There are three subspecies of U. dioica. Details are given at the page bottom and an illustration is in the photos below.
Varieties: Three - see notes below photos.
Above: The inflorescence of Stinging Nettle. Illustration by William Curtis.
Below: 1st photo - The stem with its tiny stinging hair and very fine surface hair. 2nd photo - this stme has more numerous non-stinging hair - the stinging hair project outward. 3rd photo - The drooping flower cluster. These contain either male or female flowers.
Below: 1st photo - A seed cluster in late fall. 2nd photo - The individual seeds are just over a millimeter wide and less than 2 mm long, with a deltoid shape.
Below: The underside of the coarsely toothed leaf. Leaves are opposite in pairs on this nettle and the underside has stinging hair.
Below: A comparion of Stinging Nettle's three subspecies and Wood Nettle. Both images ©Flora of North America
Notes: Stinging Nettle has long been in the Garden area. Eloise Butler catalogued it on Sept. 7, 1907. It is widely distributed in the United States, Europe, Asia and is native to most counties in Minnesota and is generally classified as an unwanted weed although there is a considerable history of both practical use and medicinal use of this plant from the middle ages to well into the 20th century and it is a butterfly host.
Varieties: U. dioica is the only species of Urtica found in Minnesota There three subspecies, subsp, gracilis, subsp. holosericea and subsp. dioica, but the latter two are not distributed in Minnesota. Subsp dioica has the sexes on separate plants and both upper and lower leaf surfaces have stinging hairs. Subsp. holosericea, like subsp. gracilis, has both sexes on the same plant, but stems are softly hairy with more numerous stinging hair and the leaf upper side has soft to stiff hairs. It is primarily found in the western and southwestern states. Diagram shown above.
Toxicity: Species of Urtica cause immediate contact dermatitis and must be handled with gloves while wearing proper clothing. When used as food, leaves and stems must be cooked properly before eating. The underside of leaves (usually) and the stem (mostly) have many small hollow hairs that contain antigenic proteins and formic acid. When these needle like hair penetrate the outer skin layer these chemical contents are injected causing an immediate burning rash.
Lore and Uses:
Edibility: This is a highly nutritious plant, high in iron, calcium, potassium, vitamins A, C and D. When cooked, the harmful ingredients are neutralized and the leaves can be treated like a spinach for spring greens or used for tea. Young plants prior to blooming should be used as older ones become fibrous (see below) and after blooming the leaves develop cystoliths which irritate the urinary tract if eaten in large amounts. Nettles saw widespread use as a foodstuff. Walter Scott discusses them in Rob Roy, Pepys refers in his diary of 1661 to eating Nettle Porridge which he thought to be very good. Victor Hugo included some discourse on Nettle usage in “Les Miserables”. Grieve (Ref.#7) gives recipes for Nettle Pudding and Nettle Beer. Nettle beer, like Nettle tea would have a slight laxative effect. Prior to cooking, the leaves can be soaked in warm water for 10 minutes, then spooned out (don't reach in) and then dispose of the water. This pre-rinse assures that the formic acid will be broken down in cooking.
Medicinal: As species of Urtica (such as Urtica dioica) grow worldwide, there is considerable old literature as to folk and medicinal use. There are 17th century Russian tracts on its use. The most common medicinal use was as a diuretic, an astringent and a tonic. It is also a styptic - something which checks the flow of blood from the surface (acting very quickly); by the use of powdered root or softened and bruised leaves, Nettle has few equals in that regard. It was recommended for nosebleed that a small piece of fine cloth be moistened with Nettle juice and placed in the nostril. Several references list a use of the fresh leaves or stems as a “counter-irritant”, that is, it is applied to the skin where there is another painful irritation such as arthritis. The best explanation for that effect is that the nettle sting took ones mind off the other pain. However, the juice of the Nettle is a complete antidote for its own sting. Likewise, the juice of Dock, particularly Yellow (Curly) Dock, has the same effect. Grieve (Ref.#7) reports on the old English Saying “Nettle in, dock out. dock rub nettle out”. Densmore (Ref.#5) reports its use among the Minnesota Chippewa for dysentery and for stoppage of urine.
There are many references to Nettle preparations involving the seeds and the flesh of the plant for a hair tonic - i.e. “restorer”; so many references that one could assume one might have had some success with it prior to today's preparations. The presence of formic acid, mineral salts and carbonic acid was the key. One can find much more in the references.
Practical Uses: Besides beer as mentioned above, the most practical use for Nettle is as a substitute for Cotton. The fiber of Nettle is similar to Hemp and Flax and thus it can be used for making cloth, sacking, cordage, etc. Nettle produces less fiber than Flax. It’s fibers varying from 3/4 to 2 1/2 inches. The upper sizes equal the best Egyptian Cotton. Plants that grow in good loam, such as near ditches and other moist sources produce the best fiber. Nettle is so effective for making cloth that when Germany and Austria were short of Cotton in 1916 - 1918 during the Great War they resorted to collecting huge quantities of Nettle. In 1916 alone 2.7 million kilograms were collected for cloth production. In 1917 The British analyzed some German overalls and found they were made of 85% nettle. It does not take dye the way wool does because of its microscopic structure, but there is nothing else close to it for making cloth when you are short of Cotton. Hans C. Andersen refers to coats being woven of Nettle in the story “The Princess and the Eleven Swans.”
If humans can like to eat them, so can the animals. The plant makes great fodder once it has been allowed to wilt and begin to dry. Then the stinging effects have dissipated [Note: In some species of Urtica dissipation is not complete by drying]. While a number of insects may feed on the plant, it is distasteful to flies and a bunch of Nettle near foodstuffs can keep flies away. A decoction of Nettle produces a permanent green dye - widely used in old Russia.
Butterflies: Rough as the plant is, you can see it has had many practical uses. Today, a most important reason to leave some growing is that the plant is host to several butterflies such as Milbert's tortoiseshell. Our admired Red Admiral, Vanessa atalanta, uses this plant as a host for its larvae in the southern states where the butterfly over-winters. Others that use the plant are the Eastern Comma, the Question Mark and the Satyr Comma.
There are many references to use for Nettle. Good information will be found in Hutchens (Ref.#12), Moore (Ref.#30), Tilford (Ref.#39) and Grieve (Ref.#7). Grieve has by far the most detail.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"