Ranuncillacese, an order of thalamifloral dicotyledons comprising about 500 species in about 30 genera. With the exception of Clematis (q.v.) they are-herbs, with radical or scattered leaves and flowers specially characterised by the absence of any cohesion or adhesion among their parts. These flowers are often monosymmetric, being nearly always nectariferous and insect-fertilised. They are pentamerous; but the petals are frequently absent or aborted, the stamens are indefinite in number, and the carpels may be one, two, three, five, or indefinite. The sepals are imbricate and deciduous, the petals and stamens hypogynous, and the seeds albuminous. The fruit is apocarpous and generally dry, consisting either of achenes (q.v.) or follicles (q.v.). Almost all members of the order have acrid properties, and they belong mainly to temperate and cold regions. Among the genera are Clematis, Anemone, Ranunculus, from which the order takes its name, and which includes the buttercups, Caltha, the marsh-marigold, Helleborus, including the Christmas rose, Aquilegia, the columbines, Delphinium, the larkspurs, Aconitum, and Pasonia, most of which have been treated separately under their English names (q.v.).