Ranunculus (Lat., a little frog, some of the species growing in wet places where frogs abound), the botanical name of a large genus of plants, the common species of which are popularly known as buttercup, kingcup, or crowfoot. The genus gives its name to a large family, the ranunculaceoe, which comprises plants widely differing in their external appearance, many of which are among the best known and most showy wild and garden plants; the anemones, columbines, larkspurs, aconites, paeonies, and others belong here. In modern systematic works upon botany this family is placed at the head of the list, and is the one with which the student first makes acquaintance, examples being found almost everywhere; the flowers are usually rather large and the structure distinct and easily made out. The ranunculaceoe consist mainly of herbs (rarely undershrubs or woody climbers) with a colorless, acrid juice; they are polypetalous, or when the petals are absent the calyx is colored like, and is often mistaken for, the corolla; the stamens numerous, and the pistils (usually more than one) distinct (rarely somewhat united), one-celled, and one- to many-ovuled. The leaves when not radical are alternate, or in a few genera opposite, often much divided, and have sheathing petioles.
In ranunculus itself there are five sepals and five flat petals, each with a little scale or pit at its base; numerous pistils, which ripen into a head of mostly flattened, one-seeded fruits or akenes; sometimes the sepals and petals are only three, or the petals more than five, and sometimes white instead of the usual yellow. There are about 160 species, which are distributed all over the world; in the eastern states there are some 20 species, including four introduced from Europe, and in the far west several others. Some are truly aquatics, others abound in muddy and swampy places; one is found only at the seaside or by the shores of the great lakes, and others are common weeds. All have an acrid juice, which in some is so powerful as to blister readily, and was formerly used as a vesicant; the leaves are said to be used by the professional beggars of London to keep up ulcers with which to excite sympathy. This acridity is dissipated in drying; one of the most active, very common in the meadows in the older states, is cut in large quantities with the grass, and is eaten with the hay, though animals at pasture avoid it in the fresh state.
The species common as meadow weeds are the bulbous and the tall buttercups; the first named (R. bul-bosus), more abundant in New England than elsewhere, is readily distinguished by the bulblike base to the stem, and its very large flowers, more than an inch broad, and of a very deep shining yellow, blooming from May to July. Tall buttercup (R. acris) is more widely distributed and grows twice as high as the preceding, in rich soil being 3 ft. or more tall; its stem is not bulbous, and its smaller and paler flowers appear in June and continue till August and later. There are double varieties of both these species, common in gardens as double buttercups, the boutons d'or of the French. The creeping crowfoot or buttercup (R. repens) is a very common species, forming long runners which root at every joint; it is extremely variable, and often found without runners; it is a native, and somewhat troublesome in moist meadows and pastures. The yellow water buttercup (R. multifidus or R. Purshii of the older books) has its leaves very much dissected into filiform divisions, and bears a large bright yellow flower; its handsome foliage makes it an excellent plant for an aquarium.
The remaining natives are only of botanical interest. - Among the exotic species cultivated in gardens is R. aconitifolius, which grows 2 ft. or more high, and has large white flowers; there is a double form of it, with flowers like minute camellias, which bears the fanciful name of "fair maids of France." Some other hardy species are grown in European gardens, but rarely in ours. - The Asiatic ranunculus (R. Asiaticus) ranks as a florist's flower. The roots, which are imported in autumn by the seedsmen with Holland bulbs, are in small clusters, fleshy, an inch or more long, and apparently without signs of life; they are not hardy generally in the northern states, and if planted in the garden must be well covered; they are often cultivated in pots, in the same manner as bulbs, and give large very double flowers, 2 in. across, and of a great variety of colors.
Ranunculus - Section of Flower.