Urtica is a genus of flowering plants in the family Urticaceae. Many species have stinging hairs and may be called nettles or stinging nettles (the latter name applying particularly to U. dioica). The generic name Urtica derives from the Latin for 'sting'.
Due to the stinging hairs, Urtica are rarely eaten by herbivores, but provide shelter for insects. The fiber has historically been used by humans, and cooking preparations exist.
Description
Urtica species grow as annuals or perennial herbaceous plants, rarely shrubs. They can reach, depending on the type, location and nutrient status, a height of . The perennial species have underground rhizomes. The green parts have stinging hairs. Their often quadrangular stems are unbranched or branched, erect, ascending or spreading.
Most leaves and stalks are arranged across opposite sides of the stem. The leaf blades are elliptic, lanceolate, ovate or circular. The leaf blades usually have three to five, rarely up to seven veins. The leaf margin is usually serrate to more or less coarsely toothed. The often-lasting bracts are free or fused to each other. The cystoliths are extended to more or less rounded.
In 1874, while in Collioure (south of France), French botanist Charles Naudin discovered that a strong wind lasting 24 hours rendered the stinging hairs of nettles harmless for an entire week.
Taxonomy
Phylogeny
The last common ancestor of the genus originated in Eurasia, with fossils being known from the Miocene of Germany and Russia, subsequently dispersing worldwide. Several species of the genus have undergone long distance oceanic dispersal, such as Hesperocnide sandwicensis (native to Hawaii) and Urtica ferox (native to New Zealand).
Species
A large number of species included within the genus in the older literature are now recognized as synonyms of Urtica dioica. Some of these taxa are still recognized as subspecies. Genetic evidence indicates that the two species of Hesperocnide are part of this genus.
Species in the genus Urtica, and their primary natural ranges, include: Urtica andicola Webb Urtica angustifolia Fisch. ex Hornem. China, Japan, Korea Urtica ardens LinkChina Urtica aspera Petrie South Island, New Zealand Urtica atrichocaulis (Hand.-Mazz.) C.J.Chen Himalaya, southwestern China Urtica atrovirens Req. ex Loisel. western Mediterranean region Urtica australis Hook.f. South Island, New Zealand and surrounding subantarctic islands Urtica cannabina L., Western Asia from Siberia to Iran Urtica chamaedryoides Pursh (heartleaf nettle), southeastern North America Urtica dioica L. (stinging nettle or bull nettle), Europe, Asia, North America Urtica dioica subsp. galeopsifolia Wierzb. ex Opiz (fen nettle or stingless nettle), Europe. (Sometimes treated as a separate species Urtica galeopsifolia.) Urtica dubia – illegitimate synonym of U. membranacea Urtica ferox G.Forst. (ongaonga or tree nettle), New Zealand Urtica fissa E.Pritz. China Urtica gracilenta Greene (mountain nettle), Arizona, New Mexico, west Texas, northern Mexico Urtica gracilis Aiton (slender nettle), North America and parts of South America Urtica hyperborea Jacquem. ex Wedd. Himalaya from Pakistan to Bhutan, Mongolia and Tibet, high altitudes Urtica incisa Poir. (scrub nettle), Australia, New Zealand Urtica kioviensis Rogow. eastern Europe Urtica laetivirens Maxim. Japan, Northeast China Urtica lalibertadensis Weigend Urtica linearifolia (Hook.f.) Cockayne (creeping or swamp nettle), or Urtica perconfusa, an at risk endemic climber, New Zealand Urtica mairei H.Lév. Himalaya, southwestern China, northeastern India, Myanmar Urtica massaica Mildbr. Africa Urtica membranacea Poir. ex Savigny Mediterranean region, Azores and Madeira Urtica morifolia Poir. Macaronesia Urtica minutifolia Griseb. Bolivia Urtica parviflora Himalaya (lower altitudes) Urtica peruviana D.Getltman Perú Urtica pseudomagellanica D.Geltman Bolivia Urtica pilulifera L. (Roman nettle), southern Europe Urtica platyphylla Wedd. Kamchatka, Sakhalin, Japan Urtica procera Mühlenberg (tall nettle), North America Urtica pubescens Ledeb. Southwestern Russia east to central Asia Urtica rupestris Guss. Sicily (endemic) Urtica sondenii (Simmons) Avrorin ex Geltman northeastern Europe, northern Asia Urtica taiwaniana S.S.Ying Taiwan Urtica thunbergiana Siebold & Zucc. Japan, Taiwan Urtica triangularis Hand.-Mazz. Urtica urens L. (small nettle or annual nettle), Europe, North America Urtica urentivelutina Weigend
Etymology
The generic name Urtica derives from the Latin for 'sting'.