PRIMULALES

primrose order of flowering plants, belonging to the class Magnoliopsida (dicotyledons; characterized by two seed leaves). It comprises 3 families and about 1,900 species of plants distributed on every continent. Leaves of the Primulales are simple (i.e., they have a single blade), and flower parts occur in fives; other attributes separate the order into families and genera. Of the three families, two-Theophrastaceae and Myrsinaceae-are mainly tropical. They consist mostly of trees and shrubs with evergreen leaves, small flowers, and fleshy fruits. The third family, Primulaceae, occurs chiefly in north temperate and Arctic regions. It consists primarily of herbaceous annuals and perennials with large flowers and capsules (dry fruits) that split to release their seeds. The Primulaceae, with approximately 800 species, is noted for many horticulturally valuable plants. The primroses (Primula), which are familiar garden plants, account for nearly one-half of the species, with major centres of distribution in China and the Himalayas. More than 100 species and hybrids are on horticultural and botanical lists as suited for cultivation. Other familiar plants of this family include Cyclamen, creeping Jenny (Lysimachia nummularia), and the shooting star (Dodecatheon). The Theophrastaceae is represented in Hawaii and the American tropics. Only a few of its 100 species are in cultivation as ornamentals in temperate regions. Flowers of this family have, in addition to five stamens, a cycle of five expanded staminodes (sterile stamens), alternating with petals. Seeds are large and yellow. The small tree Jaquinia barbasco of the West Indies is widely grown in the tropics for its foliage, fragrant white flowers, and orange fruits. It yields a poison used to stupefy fish. The Myrsinaceae, most abundant in the tropics and the Southern Hemisphere, has extensions of distributions into Mexico and Florida and to Japan in the Pacific regions. In nature, the family may often be identified by glands, or resin ducts, that appear as tiny, translucent spots in its evergreen leaves. Staminodes, if present, are not expanded, and seeds are small and dark coloured. Only a small fraction of its 1,000 species are in cultivation. Abundant, long-lasting, bright berries make Ardisia crenata, the coralberry, a favourite greenhouse plant. A. primulifolia is the only herb of this family. Maesa indica, a small tree of the Old World, produces an edible, creamy-white fruit. The cape myrtle (Myrsine africana), an ornamental shrub distributed from the Azores to Taiwan, is grown for its red, berrylike drupes. It is used locally as a tapeworm remedy. All species of Primulales produce abundant seed. In addition, some species commonly reproduce by vegetative propagation. For example, runners of a weedy pimpernel (Anagallis arvensis) and rhizomes of Lysimachia thyrsiflora, both members of the primrose family, produce roots at nodes. These horizontal stems separate to establish separate plants. Some genera develop flowers singly, but, in most members of this order, inflorescences of various configurations are produced. A calyx and corolla, of five joined sepals and petals, respectively, and similar numbers of stamens and carpels (constituting the pistil) are almost universal in the Primulales.