Biological Flora of the British Isles: Urtica dioica L.

Abstract

Summary1. This account presents information on all aspects of the biology of Urtica dioica that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. 2. Urtica dioica is a tall, usually dioecious, rhizomatous, perennial herb with numerous stinging hairs, probably native in fens and semi-natural ancient woodlands, but widely naturalized in a range of habitats and abundant throughout the British Isles. British material is mainly ssp. dioica which also extends throughout Europe, and locally ssp. galeopsifolia (without stinging hairs) which is also found in western, central and eastern Europe. 3. Urtica dioica is a moderately shade-tolerant species, which occurs on most moist or damp, weakly acid or weakly basic, richly fertile soils. 4. A highly competitive ruderal species, Urtica dioica often forms monospecific stands which are not infrequently the product of a single individual that has spread by means of horizontal rhizomes. 5. Urtica dioica has frequently been described as a nitrophile, but there are many soils in which the supply of inorganic nitrogen is adequate for growth. However, there are other soils in which growth is checked with symptoms of severe phosphorus deficiency unless soluble phosphate is added to the soil. This is especially so in the long-established deciduous woodlands, and where there has been no addition of fertilizers to the soil. The growth responses of U. dioica to the availability, source and utilization of nitrogen and phosphorus have been examined experimentally in some detail. 6. Urtica dioica with its stems and leaves densely covered with stinging hairs, which release potential pain-inducing toxins when brushing contact is made with them, is rarely eaten by cattle and rabbits, but is palatable to some species of snail. It is the food plant of the larvae of a number of attractive butterflies and other phytophagous insects. 7. Male clones of U. dioica flower in advance of female clones. The pollen grains are extremely small. It is usually wind-pollinated, but occasionally insect-pollinated. 8. The low seed mass of U. dioica enables the production of vast numbers of seeds. Few of the seeds germinate in the period immediately following dispersal, and the species maintains a seed bank that changes little in size with season and is large in relation to annual seed production.Key-words: communities, conservation, ecophysiology, geographical and altitudinal distribution, germination, herbivory, nutrients, reproductive biology, soils Urticaceae, Urtica dioica L. (stinging nettle, common nettle) is a perennial herb with an extensive sympodial system of rhizomes and stolons, rooting at the nodes and giving rise in spring to aerial shoots up to 1.5-2 m or (rarely) 3...

Changes in the productivity of wild and cultivated stinging nettle (Urtica dioica L.) as influenced by the planting density and crop age

“…Klimešova (1994) have reported that floods significantly reduce the survival of young Urtica plants, and reduce the biomass of older plants without killing them. Taylor (2009) states that Urtica dioica ssp. dioica cannot survive flooding of its roots and rhizomes for long periods, as it does not have any special adaptation to anoxic conditions.…”

Light interception principally drives the understory response to boxelder invasion in riparian forests

“…Since dominant tree species is the common parameter among the sites, we can suspect dominant tree species to have a principal effect on canopy cover which represents an integrated measure of the diverse parameters that can affect light interception in forests (Canham and Burbank 1994). Although U. dioica is a shade-tolerant species, it has been reported to be absent from areas where available light is less than 5-10% of full incident light (Olsen 1921;Taylor 2009). In the greenhouse, the most frequently observed value in natura under boxelder (PAR 8) induced a 50-fold reduction of U. dioica aboveground biomass, as compared to the value observed under white willow stands (PAR 48).…”

“…In the context of white willow forest decline (James 1996;Steiger et al 1998), boxelder is expected to continue its spread along European riparian corridors, as exemplified in southwest France. Indirect consequences of understory decline must also be considered, such as a decrease in abundance and diversity of Urtica-associated fauna and microflora (Taylor 2009), and intensified erosion due to decreased sediment trapping by the reduced riparian herbaceous layers (Tickner et al 2001).…”

Morfologia, desenvolvimento e aspectos da flor em espécies de Urticaceae Juss

“…Dois tipos de tricomas foram encontrados, os capitados, compostos de uma cabeça unicelular ou pluricelular com um pedúnculo pluricelular ou do tipo digitiforme, compostos de cabeça e pedúnculo pluricelulares encontrados nas folhas e inflorescências, porém ainda não há informações se esses tricomas são os descritos na literatura como urticantes (A. M. Mantoku -comunicação pessoal), já que sua morfologia não se enquadra nesta caracterização e análises de composição química do exsudato não foram realizadas. Os tricomas urticantes, quando em contato com a pele humana, liberam diversas substâncias tais como a histamina, acetilcolina e serotonina (Collier & Chesher 1956), que causam ardor, vermelhidão e sensação de queimadura , Taylor 2009, Kissmann & Groth 2000, Gangadhara et al 1977. Esses tricomas devem desempenhar um papel importante na defesa da planta contra herbívoros (Geltman 1992, Tuberville & al.…”

“…O pistilódio, descrito para as flores estaminadas de algumas espécies da família, em alguns casos, parece fazer parte de um mecanismo bastante elaborado da estrutura floral, indicando uma importante adaptação na dispersão do grão de pólen pelo vento, comum na família . Espécies anemófilas compartilham algumas características que permitem a otimização da dispersão dos grãos de pólen pelo vento, como flores díclinas e inconspícuas, arranjadas em inflorescências densas, filetes longos, grande quantidade de grãos de pólen pequenos, estigmas com uma ampla superfície e pequeno número de óvulos Friedman & Barrett 2008, 2009Leins & Erbar 2010), sem atrativos visuais ).…”