Although not large, the Solanaceae, or Nightshade family, is certainly one of the most economically important plant families. It includes about 2,500 species in 90 genera. The potato/tomato genus, Solanum, includes about one-half of the species. Many place the family third in worldwide importance to people, behind the grasses and the legumes . This ranking is based on the many food and drug plants found in this genus. Virtually all of the edible plants were prehistoric domesticates of Latin America, except eggplant (from India). Among the species that had dramatic effects on world cuisine and history are potatoes, tomatoes, and hot (chili) peppers. Prior to 1492, there were no hot peppers in China or Southeast Asia, no tomatoes in Italy, no potatoes in Ireland or Russia, and no tobacco in Europe. In addition, several minor domesticates from the New World have had a lesser impact: tamarillo, tomatillos (the "ground cherries" of North America), and pepinos. Pepinos are eaten fresh, whereas the other two are usually eaten cooked; tomatillos together with chile peppers constitute the salsa verde popular in the Southwest United States.
The family is sometimes referred to as the paradoxical nightshades because it includes so many domesticates of such importance—the modified stems that constitute the tubers of potatoes follow only corn, wheat, and rice in production as world crops—and at the same time, so many toxic plants. Although the family's origin and greatest diversity are in Latin America, the Nightshades first became notorious in written history based on the toxic compounds of Mediterranean plants. The strong tropane alkaloids like atropine and scopolamine that make henbane, belladonna, and mandrake so poisonous are used in medicine today. Atropine is used to promote pupil dilation in ophthalmology (the wider pupils the drug promotes were taken advantage of by Italian women to make their eyes more attractive— hence the name, belladonna). However, the most significant drug plant in the family is tobacco, from the New World.
In addition to direct economic importance, various members have been significant in plant physiology (studies of day length and flowering), biotechnology, and molecular biology. The family includes a number of ornamentals, most prominently, Petunia, Salpiglossis, and Brunfelsia.
The herbs, shrubs, trees, and lianas (climbing vines) in the family grow in habitats from deserts to tropical forests, from sea level to the Andes Mountains. The leaves are generally alternate, petiolate, and simple, although they can be lobed or compound, and are often covered with hairs and sometimes with prickles (trichomes). The unusual vascular tissue has internal phloem. The flowers, solitary or in inflorescences , are usually radially symmetrical, pentamerous , and have a calyx and corolla united in short or long tubes. Thus, the corolla can be tubular, rotate, or campanulate . The mostly hermaphroditic flowers bear stamens attached to the corolla tube with anthers that break open to release pollen, by longitudinal slits, or by terminal pores in Solanum. The gynoecium consists of a single pistil and generally has a superior two-carpellate, two-locular ovary with numerous ovules. Except in Solanum, a floral nectary is often present at the base of the ovary. The fruit is mostly a juicy berry or a dry capsule, characteristically with the calyx persistent. Many species are pollinated by insects, although some are pollinated by hummingbirds, perching birds, or bats.
see also Potato; Potato Blight; Psychoactive Plants; Tobacco; Trichomes.
Gregory J. Anderson