LYSIMACHIA, in botany, a genus of the pentandria monogynia class. The calix is rotated; and the capsule is roundish, with a sharp point, and contains ten valves. There are eleven species, five of them natives of Britain, viz. the vulgaris, or yellow willow-herb; the thiriflora, or tufted loose-strife; the nemorum, or yellow pimpernell of the woods; the nummularia, or money wort; and the tenella, or purple money-wort.