Stinging Nettle (Urtica Dioica) is a perennial herb up to 170 cm high with a long creeping branched rhizome and thin roots in nodes. Stems are erect, tetrahedral, furrowed. The leaves are opposite, petiolate, ovoid-lanceolate, large-serrated. The stem and leaves are covered with long burning and short hairs, called trichomes. The hair shells are siliceous, so formic acid and histamine flow from a broken hair, causing a stinging sensation when contacted by humans. The flowers are small, green. The fruit is an ovoid nut of yellowish-gray color. Stinging Nettle blooms from June to September.