What is "urtica dioica"

Nettle \Net"tle\, n. [AS. netele; akin to D. netel, G. nessel, OHG. nezz["i]la, nazza, Dan. nelde, n["a]lde, Sw. n["a]ssla; cf, Lith. notere.] (Bot.) A plant of the genus Urtica, covered with minute sharp hairs containing a poison that produces a stinging sensation. Urtica gracilis is common in the Northern, and Urtica cham[ae]dryoides in the Southern, United States. The common European species, Urtica urens and Urtica dioica, are also found in the Eastern united States. Urtica pilulifera is the Roman nettle of England. Note: The term nettle has been given to many plants related to, or to some way resembling, the true nettle; as: Australian nettle, a stinging tree or shrub of the genus Laportea (as Laportea gigas and Laportea moroides); -- also called nettle tree. Bee nettle, Hemp nettle, a species of Galeopsis. See under Hemp. Blind nettle, Dead nettle, a harmless species of Lamium. False nettle ( B[ae]hmeria cylindrica), a plant common in the United States, and related to the true nettles. Hedge nettle, a species of Stachys. See under Hedge. Horse nettle ( Solanum Carolinense). See under Horse. nettle tree.

1. Same as Hackberry.

2. See Australian nettle (above).

   Spurge nettle, a stinging American herb of the Spurge family ( Jatropha urens).

   Wood nettle, a plant ( Laportea Canadensis) which stings severely, and is related to the true nettles.

   Nettle cloth, a kind of thick cotton stuff, japanned, and used as a substitute for leather for various purposes.

   Nettle rash (Med.), an eruptive disease resembling the effects of whipping with nettles.

   Sea nettle (Zo["o]l.), a medusa.

Urtica dioica, often called common nettle or stinging nettle (although not all plants of this species sting), is a herbaceous perennial flowering plant in the family Urticaceae. It is native to Europe, Asia, northern Africa, and western North America, and introduced elsewhere. It is the best-known member of the nettle genus Urtica. The species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation when contacted by humans and other animals. The plant has a long history of use as a source of medicine, food, and fibre.