Onagraceae A. L. Jussieu
Peter C. Hoch and Peter H. Raven
Perennial or annual herbs (in Pakistan), shrubs or rarely trees. Leaves simple, opposite or spirally arranged, entire or toothed; stipules present or absent. Flowers actinomorphic or zygomorphic, hermaphrodite (in Pakistan), solitary or in axils of leaves or in racemes, 2-7-merous. Floral tube present or absent. Sepals 2-7, valvate. Petals 0-7, free. Stamens as many as or twice as many as the sepals. Anthers versatile or basifixed; pollen shed singly or in tetrads, almost always united by viscin threads. Ovary inferior, 1-5-locular; style single; stigma lobed, clavate or globose. Fruit a capsule, berry or nut, loculicidal or indehiscent. Seeds anatropous, lacking endosperm, smooth or variously papillose, with a coma or wings or lacking both.
A family of 17 genera and about 650 species, worldwide but best represented in western North America. Represented in Pakistan by four genera, of which only Oenothera is not native.
[Treatment of Circaea by David E. Boufford, Section of Botany, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA.; of Oenothera by Warren L. Wagner, Washington University and Missouri Botanical Garden, St. Louis, Missouri, USA.; of Epilobium and Ludwigia by Peter Hoch].