VIOLALES

violet order of dicotyledonous flowering plants, a division of the subclass Dilleniidae. The order consists chiefly of shrubs and trees, but it also contains herbaceous plants, including the large family of violets. The order Violales has recently been considered to be an offshoot of the order Theales; the families of Violales have been thought to be ancestors of, or transitional to, a dozen other orders in the Dilleniidae and other subclasses. The Violales nearly merge with the Theales, Malvales, Salicales, Capparales, and possibly others through various transitional genera and families. the violet order of flowering plants, belonging to the class Magnoliopsida (dicotyledons; characterized by two seed leaves). The Violales order consists chiefly of shrubs and trees, but it also contains herbaceous (nonwoody) plants, including the large family of violets. Violales is closely related to the orders Theales, Malvales, Salicales, Capparales, and possibly others, and recently it has even been considered an offshoot of the Theales by some authorities. As a consequence, there are many different classifications of the components of the order, with various authorities including as few as 9 or as many as 24 families in it. A conservative listing includes the families Violaceae, Flacourtiaceae, Cucurbitaceae, and Passifloraceae within the order. Except for the cosmopolitan violet family (Violaceae), the order is mostly confined to tropical and subtropical regions. Its members are typically small trees and shrubs that grow as low vegetation beneath the taller trees of forests. They rarely, if ever, form the dominant plant life of an area. The family Cucurbitaceae, which is occasionally placed in its own order, includes such food plants as gourds, melons, squashes, and pumpkins. Among its best-known species are the watermelon (Citrullus lanatus), the cucumber (Cucumis sativus), cantaloupes and muskmelons (Cucumis melo), and the gourds, melons, squashes, and pumpkins of the genus Cucurbita. Another well-known family in the order is the Violaceae, members of which are found on all continents. Violets, both wild and cultivated varieties, are favourite ornamental garden plants. The passion-flower family (Passifloraceae) contains many tendril-bearing vines with characteristic flowers. A few of the many species in the large Indian plum family (Flacourtiaceae) produce small fruits used in the tropics for jams and preserves. The members of the order vary widely in their characteristics. Most members of the Violales order are shrubs or small treees, either evergreen or deciduous. Flowers generally consist of five sepals and five petals and exhibit radial symmetry; most have the male and female reproductive structures in the same flower. All but one genus in the order are characterized by parietal placentationthat is, the seeds are attached to the inner wall of the fruit. The fruit is either a berry or a dry capsule with a number of openings for release of the seeds. Leaves are simple, grow alternately and spirally on the plant stems, and have paired stipules (leaflike appendages) at the bases of the leaf stalks. Additional reading W.H.A. Hekking, Violaceae, pt. 1, Rinorea and Rinoreocarpus (1988); John Vanderplank, Passion Flowers and Passion Fruit (1991); Charles B. Heiser, Jr., The Gourd Book (1979); David M. Bates, Richard W. Robinson, and Charles Jeffrey (eds.), Biology and Utilization of the Cucurbitaceae (1990); Mildred L. Thompson and Edward J. Thompson, Begonias: The Complete Reference Guide (1981), a general, well-documented and well-illustrated reference; Lyman B. Smith et al., Begoniaceae (1986), the most inclusive set of keys to all recognized species and varieties of Begonia, with illustrations.