A New Species of Ranunculus (Ranunculaceae) from Hokkaido, Northern Japan

Abstract

A new species of Ranunculus (Ranunculaceae), R. horieanus Kadota, is described from Hokkaido, northern Japan. It resembles R. acris subsp. novus (H. Lév. & Vaniot) Vorosch. [= R. acris var. nipponicus H. Hara] but is distinguished from the latter by having obovate petals with short claws, hemispherical, small nectary pits, smaller nectary appendages, bi-bracteolate pedicels, patent sepals, divaricate, elongated branches and pedicels at fruiting time and smaller fruiting heads. Ranunculus horieanus is distributed in the northernmost part and the central part of Hokkaido and grows along mountain streams of lowlands (alt. 100-200 m).