meadow rue, any plant of the genus Thalictrum of the family Ranunculaceae (buttercup family). Most are tall perennials (up to 7 ft/2.1 m high) bearing summer flowers with showy, pendent tassels of long stamens, greenish sepals, and no petals. Meadow rues are found in moist, open places throughout northern temperate regions; in the United States they are especially abundant in the Northeast. A few species are cultivated for ornament. The European herb called rue is an unrelated plant. Meadow rue is classified in the division Magnoliophyta, class Magnoliopsida, order Ranunculales, family Ranunculaceae.