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Buttercups and crowfoots are about 275 species of plants in the genus Ranunculus, family Ranunculaceae. Buttercups mostly occur in cool and temperate regions of both hemispheres of the world, including mountains in tropical latitudes.

Buttercups are annual or perennial, and they are herbaceous plants, dying back to the ground surface before the winter. The leaves of terrestrial species are simple or compound. However, the underwater leaves of aquatic buttercups can be very finely divided. Some of the aquatic buttercups have dimorphic foliage, with delicately divided leaves in the water, and distinctly broader leaves in the atmosphere.

The flowers of buttercups have numerous stamens and pistils, arranged in a spiral fashion on a central axis. The flowers of most species of buttercups are radially symmetric and showy, owing to their large, yellow petals. However, some species have red or white petals. The petals secrete nectar, important in attracting the insects that are the pollinators of most buttercups. There are usually five sepals, but these generally fall off the flower relatively soon. The fruits are loose heads of one-seeded fruits called achenes.

Many species of buttercups are native to North America. The wood buttercup (Ranunculus abortivus) is a widespread species of rich, temperate forests. The yellow water-crowfoot (R. gmelini) is a widespread species of freshwater marshes and shores, while the seashore-buttercup (R. cymbalaria) occurs in salt marshes and estuaries. Many native species of buttercups occur in alpine and arctic tundras, for example, the Lapland buttercup (R. lapponicus) and snow buttercup (R. nivalis).

Several species of Eurasian buttercups have been introduced to North America where they have become widespread weeds of lawns, fields, and other disturbed places. Some of the more familiar introduced species are the tall or meadow buttercup (R. acris), the creeping buttercup (R. repens), and the corn crowfoot or hunger-weed (R. arvensis).

A few species of buttercups are used in horticulture. The most commonly used species for this purpose is the garden buttercup (R. asiaticus), available in varieties with white, red, or yellow-colored flowers. Aquatic buttercups, such as the water crowfoot (R. aquatilis), are sometimes cultivated in garden pools. Various alpine species of buttercups can be planted in rock gardens.

Meadow buttercups (Ranunculus acris). © John Buitenkant 1993, National Audubon Society Collection/Photo Researchers, Inc. Reproduced with permission.

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