Nettle (Urticaceae)

Family:

nettle family (Urticaceae)

Flowering period:

June to September

Distribution:

mainly distributed in temperate regions of both the Southern and the Northern Hemisphere, colonizes a wide range of habitats, Parietaria only present in the northern hemisphere and more common in southern Europe than northern Europe

Appearance:

annual to perennial herbaceous plants, may be covered with stinging hairs, flowers are usually radially symmetrical and with many flowers together (branched, paniculate, spiky or racemose)

Important species in Europe:

Urtica (nettles): covered with stinging hairs and bristles, leaves are arranged in a cross-opposite, leaf blades are elliptic, lanceolate, ovate or circular, serrated leaf edge, food plant for many butterfly caterpillars.

Parietaria: no stinging hairs, leaves lanceolate, flowers greenish or reddish- greenish, in balls or wrapped around the leaf axils, the central European P. officinalis prefers shady ruderal habitats and replaces nettles in riparian forests; the allergenic P. judaica also present in exposed places in the Mediterranean region and along the Atlantic coast to the Midlands (often in cracks in the walls).

Allergenicity:

pollen grains from nettle have rather low allergenicity, those of Parietaria are moderately allergenic, very difficult to distinguish the two genera in skin prick tests and pollen morphology, another European genus (Pillularia) is rare and presumably of no allergological importance

Link zum Pollenatlas: Urtica dioica