Common hemp nettle: A 15-70 cm tall, taprooted, annual herb. The square stems are covered with firm, backward pointing hairs. The leaves are elliptical to oval shaped, coarsely blunt-toothed, 3-10 cm long, and 1-5 cm wide. The tube-like flower is 1.5-2.3 cm long, purple, pink, or sometimes white, with dark markings. The flowers are densely bunched in whorls at the nodes and are protected by 1 cm long spines. The plants flower from July to August and are native to Eurasia. The plant hairs irritate skin.