Ranunculus peltatus (Ranunculus subgen. Batrachium, Ranunculaceae) is documented from aquatic wetlands of NW Iran. It is the first evidence of heterophyllous Ranunculus/Batrachium populations for Iran. The two newly found populations were identified as Ranunculus peltatus, known from a wide range of habitats in unbuffered, running or stagnant water throughout Europe. The Ranunculus peltatus group is a polymorphic group of confusable taxa, usually placed on species or subspecies rank. The distinguishing features of the known Iranian members of Ranunculus subgen. Batrachium are presented in a determination key and the role of migrating waterfowls in the dissemination of aquatic plants over long distances is discussed.
