The familiar plant known as tobacco has the more technical name of Nicotiana tabacum L. It belongs to a family of plants called the Solanaceae or Nightshade family. This family includes many familiar species besides tobacco: tomato, potato, bitter sweet, horse-nettle, ground-cherry, jimsonweed, henbane, and petunia, to mention only a few. In addition to these more distant relatives of tobacco, there are approximately 65 Nicotiana species. Morphologically, the Nicotiana species are very diverse, ranging from those resembling tobacco to the extreme types that look more like cabbage. The species are widespread geographically, with a particularly large concentration in South and Central America.
Collins, Glenn B., "Use of Wild Species in Developing Varieties" (1967). Agronomy Notes. 219.