Herbs, shrubs, or small trees, mostly of wet places, sometimes floating in open water. Leaves alternate (in Taiwan) or opposite, rarely whorled; stipules present, caducous. Flowers (3-)4-5(-7)- merous, in axils of reduced leaves. Floral tube absent, the sepals persistent after anthesis, sepals (3-)4-5(-7); petals as many as the sepals or absent, yellow or in a few species white, not deeply notched. Stamens as many as or twice as many as the sepals; pollen shed singly or in tetrads. Ovary with as many locules as the sepals, the seeds numerous in each locule. Capsules dehiscent or indehiscent.
About 80 species, pantropical but mostly in the New World, and well represented in temperate regions also. Six species and one hybrid occur in Taiwan.
Gu, H. Y., C. J. Chen, C. Q. Liu, L. J. Qu & N. S. Pan 1991. On distribution, cytology, and systematics of Ludwigia Sect. Oligospermum in China. Cathaya 3: 37-44.
Peng, C. I. 1983. Triplodidy in Ludwigia in Taiwan, and the discovery of Ludwigia adscendens (Onagraceae). Bot. Bull. Acad. Sin. 24: 129-134.
Peng, C. I. 1990. Ludwigia x taiwanensis (Onagraceae), a new species from Taiwan, and its origin. Bot. Bull. Acad. Sin. 31: 343-349.
Raven, P. H. 1963. The Old World species of Ludwigia (including Jussiaea), with a synopsis of the genus (Onagraceae). Reinwardtia 6: 627-347.
