日本産キンポウゲ属バイカモ亜属の分類について Notes on Japanese Ranunculus subgenus Batrachium

An investigation into Japanese Ranunculus subgenus Batrachium is carried out. The study is based on own collections from 20 populations in 1985 and on herbarium studies of 175 additional specimens. The importance of the following characters is outlined: total length of plants, length of submerged leaves, petiole length, presence of floating leaves, peduncle length, petal size, shape of nectaries, length of ripe achenes and hairiness of the receptacle. A morphological and morphometrical analysis gives the following result: R. yezoensis and R. kadzusensis do not belong to the R. nipponicus complex. However, R. kadzusensis is not sufficiently different from R. trichophyllus. The R. nipponicus complex is subdivided into 4 subtypes to which the rank of variety is assigned. At least two other types of plants (Anecha hybrid, Ashibetsu type) do not fit any taxon described so far. The Ashibetsu type is described as a new species. Because of the new grouping several nomenclautural problems arise.