Botanical name: Urtica dioica. The plant is known as “stinging nettle” because of its hollow hairs (tricomes) on the leaves and stem that cause a stinging sensation upon contact. Nettle leaves are harvested in the spring, once the plant has had time to mature but before it goes into flower. The leaves can be steeped as nettle tea, incorporated into herbal infusion blends, and added to soups and broths. PrecautionsNo known precautions.