Buttercup is a common name for several herbaceous plants of the genus Ranunculus [Lat, "little frog," from the wet habitat occupied by many species], family Ranunculaceae. There are an estimated 300 species distributed in temperate and arctic regions worldwide, with a few species in tropical alpine zones. In Canada there are 45 species, of which 7 are introduced Eurasian weeds.
Buttercup leaves can be simple or compound (a few species) with entire, toothed, lobed or finely divided margins. The lobed species are the source of another often-used common name, crowfoot. A few buttercups are aquatic, bearing much-divided leaves. About 40 species are cultivated as ornamentals; 2 or 3 of these have double-petalled forms. Buttercups are acrid in taste, or even poisonous. Flowers are usually yellow, but may be white, red or green. The often-shiny petals have a nectar pit (nectary) at their base, which is usually covered by scales.
Stamens and simple pistils (carpels) are numerous, pistils being arranged spirally on an elongated axis or receptacle. After fertilization, the pistils ripen into hard fruits (achenes).
See also Poisonous plants.