Description from Flora of China
Herbs perennial or annual, terrestrial or rarely aquatic. Stems usually leafy. Leaves usually both basal and along stem, lower leaves petiolate, petiole expanded into sheath at base; leaf blade simple, palmately divided, 1- or 2-ternate or, rarely, pinnate. Inflorescence a solitary terminal or leaf-opposed flower, or a simple or compound monochasium. Flowers bisexual, actinomorphic. Receptacle ± convex, sometimes forming androgynophore (Ranunculus angustisepalus). Sepals (3--)5(--7), usually greenish, occasionally dark reddish or purple, very rarely abaxial sepal appendiculate (R. angustisepalus), deciduous or, rarely, persistent. Petals (3--)5(--10), yellow, rarely white, exceptionally red (not in Flora area), base shortly clawed, with foveolate adaxial nectary pit which is sometimes covered by a scale. Stamens numerous or rarely few. Carpels numerous, sessile or rarely stalked (R. podocarpus); ovule 1 per carpel, basal; style usually present, with adaxial stigmatic tissue, sometimes absent; distinct stigma usually absent. Fruit aggregate, globose, ovoid, or cylindric, with numerous achenes. Achenes ovoid, obovoid, or slightly to strongly bilaterally compressed, smooth, sometimes tuberculate or spiny, sometimes marginate or winged along sutures, usually greenish, black in R. melanogynus. Seeds with a copious endosperm and small embryo.
Much use has to be made of the form of the leaf blade which varies from simple and entire through to ternately compound. The following terms are used in this account: 3-sect, i.e., divided almost to petiole so as to be almost compound; 3-partite, i.e., divided for half or more of the length of the leaf blade; 3-fid, i.e., divided for less than half of the length of the leaf blade; and 3-lobed, i.e., shallowly and irregularly divided. Some species are very variable and hence have been keyed out several times in the following key.
Species nos. 1–81 in this account belong to Ranunculus sect. Auricomus (Spach) Tamura, a taxonomically difficult group in which apomixis is known to occur.
About 550 species: widespread on all continents except Antarctica, mainly in N temperate regions; 125 species (66 endemic) in China.
(Authors: Wang Wencai; Michael G. Gilbert)