RANUNCULUS, familiarly known as "buttercup," or crow foot, a characteristic genus of the botanical family Ranunculaceae, The Latin name, which means a little frog or tadpole (dim. of rana, frog), was also given to a medicinal plant, which has been identified by some with the crowfoot. The members of the genus Ranunculus are more or less acrid herbs, sometimes with fleshy root-fibres, or with the base of the stem dilated into a kind of tuber (R. bulbosus). They have tufted or alternate leaves, dilated into a sheath at the base, and very generally, but not universally, deeply divided above. The flowers are solitary, or in loose cymes, and are remarkable for the number and separation (freedom from union) of their parts. Thus there are five sepals, as many petals, and numerous spirally arranged stamens and carpels. The petals have a little pit or honey-gland at the base, which is inter esting as foreshadowing the more fully developed tubular petals of the nearly allied genera Aconitum and Helleborus. The fruit is a head of "achenes"—dry, one-seeded fruits.
The genus contains a large number of species (about 300) and occurs in most temperate countries in the northern and southern hemispheres, extending into arctic and antarctic regions, and appearing on the higher mountains in the tropics. About 15 species are natives of Great Britain. R. acris, R. repens, R. bid
bosus, are the common buttercups. R. arvensis, found in corn fields, has smaller pale yellow flowers and the achenes covered with stout spines. R. lingua, spearwort, and R. flammula, lesser spearwort, grow in marshes, ditches and wet places. R. ficaria is the pilewort or lesser celandine, an early spring flower in pastures and waste places, characterized by having heart-shaped entire leaves and clusters of club-shaped roots. The section Batrachium comprises the water-buttercups, denizens of pools and streams, which vary greatly in the character of the foliage according as it is submerged, floating or aerial, and when submerged varying in accordance with the depth and strength of the current.
Inclusive of the water-buttercups, some 7o native species of Ranunculus occur in North America, widely distributed through out the continent. Representative species are R. septentrionalis, R. abortivus and R. recurvatus, of the eastern States, and R. cali f ornicus , of the Pacific coast.
The ranunculus of the florist is a cultivated form of R. asiaticus, a native of the Levant, remarkable for the range of colour of the flowers (yellow to purplish black) and for the regularity with which the stamens and pistils are replaced by petals forming double flowers.