or crowfoot, common name for the Ranunculaceae, a family of chiefly annual or perennial herbs of cool regions of the Northern Hemisphere. Thought to be one of the most primitive families of dicotyledenous plants, the Ranunculaceae typically have a simple flower structure in which each flower part may be separate rather than fused into a single organ (see flower). Many buttercups are aquatic plants, hence the Latin name for the genus Ranunculus [little frog]. The family includes numerous familiar wildflowers and many cultivated ornamentals. Well-known representatives are the aconite, anemone, baneberry, bugbane, clematis (one of the few vine genera), columbine, globeflower, hellebore, hepatica, larkspur, love-in-a-mist, marsh marigold (the American cowslip), meadow rue, and peony.
The largest genus, Ranunculus, comprises the buttercups and crowfoots, names often used interchangeably. Found throughout arctic, north temperate, and alpine regions, with species in the Andes and in subantarctic areas, this genus is characterized by glossy yellow flowers (hence the name buttercup) and deeply cut leaves (supposedly resembling crows' feet). Like some other members of the family, species of this genus contain an acrid juice that makes them unpalatable for livestock and in some species poisonous. A dozen or more species are common in every part of the United States. Among those cultivated for garden and cut flowers are some double-blossomed Old World species, e.g., the turban, or Persian, buttercup (R. asiaticus), valued for the variety of its colors (all but blue), and the creeping buttercup (R. repens), native to both North America and Europe. The fig buttercup (R. ficaria), or lesser celandine—a name more commonly applied to some plants of the poppy family—is native to W Eurasia. It is considered an invasive plant in North America.
The buttercup family is classified in the division Magnoliophyta, class Magnoliopsida, order Ranunculales.