The tomatillo, also known as the Mexican husk tomato, is a plant of the nightshade family bearing small, spherical, and green or green-purple fruit of the same name. Tomatillos originated in Mexico and were cultivated in the pre-Columbian era. A staple of Mexican cuisine, they are eaten raw and cooked in a variety of dishes, particularly salsa verde. The tomatillo is a perennial plant, but is generally grown for agriculture each year as if it were an annual.

The Solanaceae, or the nightshades, are a family of flowering plants that ranges from annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal plants, spices, weeds, and ornamentals. Many members of the family contain potent alkaloids, and some are highly toxic, but many—including tomatoes, potatoes, eggplant, bell and chili peppers—are used as food. The family belongs to the order Solanales, in the asterid group and class Magnoliopsida (dicotyledons). The Solanaceae consists of about 98 genera and some 2,700 species, with a great diversity of habitats, morphology and ecology.