ONAGRACEAE, in botany, a family of dicotyledons belong ing to the order Myrtiflorae, to which belongs also the myrtle family, Myrtaceae. It contains about 4o genera and 500 species, and occurs chiefly in the temperate zone of the New World, especially on the Pacific side. It is represented in Britain by several species of Epilobium (willow-herb), Circaea (enchanter's nightshade), and Ludvigia, a small perennial herb very rare in boggy pools in Sussex and Hampshire. In the United States, especially in the Pacific States, the family is well represented, the principal genera being Oenothera (containing as a native the evening primrose, now naturalized in certain parts of Europe), Epilobium (willow herb), and Ludvigia (false loosestrife). The plants are generally herbaceous, sometimes annual, as species of Epilobium, Clarkia, Godetia, or biennial, as Oenothera biennis evening primrose—or sometimes become shrubby or arborescent, as Fuchsia (q.v.). The simple leaves are generally entire or in conspicuously toothed, and are alternate, opposite or whorled in arrangement ; they are generally exstipulate, The flowers are often solitary in the leaf-axils, as in many Fuchsias, Clarkia, etc., or associated, as in Epilobium and Oenothera, in large showy ter minal spikes or racemes ; in Circaea the small white or red flowers are borne in terminal and lateral racemes. The regu lar flowers have the parts in fours, the typical arrangement as illustrated by Epilobium, Oeno thera and Fuchsia being as fol lows: 4 sepals, 4 petals, two alter nating whorls of 4 stamens, and 4 inferior carpels. The floral re ceptacle is produced above the ovary into the so-called calyx tube, which is often petaloid, as in Fuchsia, and is sharply dis tinguished from the ovary, from which it separates after flower ing In Clarkia the inner whorl of stamens is often barren, and in Eucharidium it is absent. In Circaea the flower has its parts in two's. Both sepals and petals are free; the former are valvate
in bud, and reflexed in the flower; in Fuchsia they are petaloid. The petals are generally convolute in bud ; they are entire (Fuchsia) or bilobed (Epilobium) ; in some species of Fuchsia they are small and scale-like, or absent (F. apetala) , The stamens are free, and those of the inner whorl are generally shorter than those of the outer whorl. The flowers of Lopezia (Central America) have only one fertile stamen. The large spherical pollen grains are connected by viscid threads. The typically quadrilocular ovary contains numerous ovules on axile placentas; the r-to-2-celled ovary of Circaea has a single ovule in each loculus. The long slender style has a capitate (Fuchsia), (Oenothera, Epilobium) or (Circaea) stigma. The flowers, which have generally an attractive corolla and honey secreted by a swollen disk at the base of the style or on the lower part of the are adapted for pollination by insects, chiefly bees and lepidoptera; sometimes by night-flying insects when the flowers are pale and open towards evening, as in evening primrose. The fruit is generally a capsule splitting into four valves and leaving a central column on which the seeds are borne as in Epilobium and Oenothera—in the former the seeds are scattered by aid of a long tuft of silky hairs on the broader end. In Fuchsia the fruit is a berry, which is sometimes edible, and in Circaea a nut bearing recurved bristles. The seeds are exalbuminous. Several of the genera are well known as garden plants, e.g., Fuchsia, Oenothera, Clarkia and Godetia. Evening primrose (Oenothera biennis), a native of North America, occurs apparently wild as a garden escape in Britain. Jussieua, a tropical genus of so species of water- and marsh-herbs, shows a develop ment of well-developed aerating tissue.