Tobacco generally refers to the leaves and other parts of certain South American plants used by Native Americans because of the nicotine the plant contains. Tobacco plants are a species of the genus Nicotiana, belonging to the Solanaceae (nightshade) family. Other members of this family of plants include potatoes, tomatoes, eggplants, belladonna, and petunias.

Two species are most widely grown for use as tobacco. The major source of commercial tobacco is Nicotiana tabacum, a broadleaf plant that grows from 3 to 10 feet tall and produces ten to twenty leaves radiating from a central stalk. Nicotiana rustica, which in fact contains higher levels of nicotine than N. tabacum, is also known as Indian tobacco. Native Americans were the first to cultivate this plant, and it was probably the tobacco offered to Christopher Columbus. The word "tobacco" entered the English language around 1565. It derives from the Spanish...