Henna is a natural orange, burnt-reddish nonpermanent dye. The tannin, or staining pigment, comes from the dried leaves and stems of the henna (aka lawsonia inermis) plant found in India, North Africa and various parts of the Middle East.
Henna is commonly used in body art (usually on the hands, face, and feet) and it can also be used as a hair dye. Since it's gentle and doesn't contain chemicals, it is a safe and wonderful hair-coloring alternative for pregnant women, or just anyone who doesn't want to run the risk of potential toxins permeating their scalp and blood stream.
Henna typically lasts about a week on the skin, but it has been known to last as long as six weeks on the hair. Mehndi, a popular henna skin-painting ritual, is used for weddings and special occasions in Hindu and Muslim cultures.