Catkin-like flowers, yellow-green. Dioecious. Leaves short-stalked, in opposite pairs. Rhizomes fleshy, yellow, far-spreading. Whole plant is covered with stinging hairs. Height: 30-120cm. Important food-plant for the caterpillars of Peacock, Small Tortoiseshell and Red Admiral butterflies.
Very common throughout Ireland, especially on phosphate-enriched soils.
Similar: Small Nettle, U. urens