The snapdragon or figwort family (Scrophulariaceae), class Dicotyledon, is composed of about 3,000 to 4,000 species and 200 genera of vascular plants. Species in this family occur on all continents except Antarctica, but are most diverse in temperate and mountain ecosystems.
Most species in the snapdragon family are perennial herbs, growing new above-ground shoots each year from a long-lived rootstock or rhizome system.
Some species are partially parasitic, obtaining some of their nutrition by tapping the roots of other species of plants. The flowers of these plants are bilaterally symmetric (each half is a mirror image of the other), and are usually pollinated by insects. Like other flowers that must attract animals to achieve pollination, those of most species in the snapdragon family are showy and attractive.
Some species are of economic importance. An alkaloid chemical variously known as digitalis, digi-talin, or digitoxin is obtained from the foxglove (Digitalis purpurea ), and is a valuable cardiac glyco-side, used in stimulating the heart. In larger doses, however, this chemical can be poisonous.
Various species in the snapdragon family are grown as attractive ornamentals in gardens and greenhouses. Some of the more commonly cultivated groups include the snapdragons (Antirrhinum spp.), slipper flower (Calceolaria ), foxglove, monkey flower (Mimulus spp.), speedwell (Veronica spp.), and beard-tongue (Penstemon spp.).
Many species in the snapdragon family are native to various habitats in North America. Some of the
most attractive wild species are the paintbrushes, such as the spectacular, scarlet painted-cup (Castilleja coc-cinea ). Other attractive native species include the tur-tlehead (Chelone glabra ), the various species of eyebright (Euphrasia spp.), and the louseworts and wood betonies (Pedicularis spp.). The latter group includes the Furbish’s lousewort (P. furbishiae ), a rare and endangered species that only occurs in the valley of the Saint John River in Maine and New Brunswick. The Furbish’s lousewort became highly controversial because of the risks posed to its survival by the construction of a hydroelectric reservoir that would have flooded most of its known habitat.
Some species in the snapdragon family have been introduced to North America, where they have become weeds. Examples of these invasive plants include the mullein (Verbascum thapsis ), displaying yellow flowers and developing a flowering stalk 6.6 ft (2 m) or more tall, and the smaller plant known as butter-and-eggs (Linaria vulgaris ).
See also Parasites.