nightshade, common name for the Solanaceae, a family of herbs, shrubs, and a few trees of warm regions, chiefly tropical America. Many are climbing or creeping types, and rank-smelling foliage is typical of many species. The odor is due to the presence of various alkaloids (including scopolamine, nicotine, and atropine), chemicals that have been used medicinally since ancient times and as stimulants, narcotics, pain relievers, poisons, and antidotes for such agents as opium and snake venom.
The chief drug plants of the family are belladonna, or deadly nightshade ( Atropa belladonna ), henbane ( Hyoscyamus niger ), mandrake ( Mandragora officinum ), Jimson weed ( Datura stramonium and other daturas in the tropics), Brunfelsia species, and tobacco ( Nicotiana tabacum ). The Old World species figured prominently in herbals and in the magic potions of alchemy. The family also includes several important food plants, e.g., the potato ( Solanum tuberosum ), the tomato ( Lycopersicon esculentum ), the peppers (except black pepper, which is a Piperaceae), or pimientos (species of Capsicum ), and the eggplant ( Solanum melongena ), the only one native to the Old World. Species of salpiglossis, petunia, butterfly flower, and the genus Solanum are among the members of the family cultivated as ornamentals.
The name nightshade is commonly restricted to members of the Solanum, characterized by white or purplish star-shaped flowers and decorative usually orange berries; among the better known species are the bittersweet, or woody nightshade ( S. dulcamara ), the buffalo bur ( S. rostratum ), the horse, or bull, nettle ( S. carolinense ), the Jerusalem cherry ( S. pseudocapsicum ), and the black nightshade ( S. niger ). The buffalo bur, originally native to the Western plains, and the horse nettle, native to the Southeast, are straggly, prickly plants which are now naturalized over most of the United States and often become pests. The berries of the horse nettle (not a true nettle botanically) have been used medicinally. Leaves of the buffalo bur served as food for the Colorado potato beetle before the advent of the cultivated potato in its vicinity. Both plants are sometimes called sandbur, properly the name for a prickly grass. The Jerusalem cherry, probably of Old World origin, is a house plant popular for its scarlet berries. The black nightshade was named for the dull black color of its berries, unusual for the genus; it is native to Europe but naturalized throughout the United States, where it is now one of the most common species of Solanum found growing wild. Because its leaves may be poisonous, it is sometimes called deadly nightshade, properly the name for the belladonna, which is not found wild in America. Nightshades are classified in the division Magnoliophyta, class Magnoliopsida, order Polemoniales, family Solanaceae.