SOLANALES

order of dicotyledonous flowering plants, a division of the subclass Asteridae. The order includes the Solanaceae and usually other families from the large 19th-century order Tubiflorae (see below Evolution). Botanists have differed as to which families should be included, but, however the order is construed, it includes some of the plants most important to human well-being. Representative species are found and used in almost every country of the world. The most important and best-known families usually included in the order are the Solanaceae (nightshades) and Convolvulaceae (morning glories). order of flowering plants belonging to the class called dicotyledon (characterized by two seed leaves). Botanists differ over which families should be included in the Solanales, but however the order is construed it contains some plants that are extremely important to human well-being. The most important and best-known families usually included in the order are the Solanaceae and the Convolvulaceae. The largest is the Solanaceae, known as the nightshade, or potato, family. The majority of its 95 genera and 2,400 species are tropical, but it is also well represented in temperate regions. Its greatest diversity is centred in western South America, extending up into Central America and Mexico. This family includes major crop plants: potatoes, tomatoes, bell peppers, eggplants, tobacco, and the garden petunia. The largest genus in the family is Solanum, with the potato (S. tuberosum) among its more than 1,000 species. The family Nicotiana has nearly 100 species, including those used for tobacco. Dodder (Cuscuta gronovii) The Convolvulaceae, or morning glory family, has more than 1,500 species distributed in 55 genera. The species most familiar in North America and Europe are twining plants, but in other parts of the world the family is represented by numerous herbs, shrubs, and small trees. The family's largest genera are Ipomoea, with about 400 species, including the morning glories, and Convolvulus, containing the convolvulus, or bindweed, and about 250 other species. The family Cuscutaceae has about 100 species of large parasitic plants, including the dodders (Cuscuta; see photograph). Two other, smaller families belonging to the order are the Goetzeaceae and Duckeodendraceae. Lianas in a tropical rainforest. The vascular tissues of lianas are modified primarily for water The phlox family, Polemoniaceae, has also been proposed as belonging to the Solanales. It includes about 300 species of herbs and some shrubs, lianas (see photograph), and small trees in about 15 or 20 genera. Most of the species are from western North America and are adapted to dry environmental conditions. The family Solanaceae contains several important medicinal plants. Jimsonweed (Datura stramonium) is the source of a potent hallucinogen, and the deadly nightshade, or belladonna (Atropa belladonna), is the source of the alkaloid atropine, which is used as a muscle relaxant and as an antidote for several types of poisoning. Additional reading William G. D'Arcy (ed.), Solanaceae: Biology and Systematics (1986); J.G. Hawkes, R.N. Lester, and A.D. Skelding (eds.), The Biology and Taxonomy of the Solanaceae (1979); J.G. Hawkes et. al., Solanaceae III: Taxonomy, Chemistry, Evolution (1991); Charles B. Heiser, Jr., Nightshades, the Paradoxical Plants (1969); Paul H. Li (ed.), Potato Physiology (1985); W.G. Burton, The Potato, 3rd ed. (1989); J.G. Hawkes, The Potato: Evolution, Biodiversity, and Genetic Resources (1990); B.C. Akehurst, Tobacco, 2nd ed. (1981); Jean Andrews, Peppers: The Domesticated Capsicums (1984).