Nettle is a perennial plant that thrives in woodlands and other shady areas throughout Europe and eastern North America. It is also called stinging nettle because the leaves are lined with stinging hairs that inject histamine into the skin when handled or brushed against, although they readily drop off when introduced to hot water or steam. Nettle is one of the first herbs to emerge in early spring and because the leaves are rich in calcium and other nutrients, it is considered a valuable tonic herb. While whole leaves are cooked like spinach or roasted to make crisp snack chips, dried nettle is used in teas or simply sprinkled into cooked foods and smoothies.