Chromosomes of Rocky MountainRanunculus

SUMMARYThe chromosome number and morphology have been studied on populations of nine species of the collective genus Ranunculus from the Rocky Mountains of North America, or R. abortivus ssp. acrolasius (2n=16), R. adonaeus (2n=16), R. alismaefolius var. montanus (2n=16), R. cymbalaria var. saximontanus (2n=16), R. inamoenus (2n=48), R. reptans (2n=32), R. Ma- counii (2n=48), R. hyperboreus ssp. intertextus (2n= 32), and R. ranunculinus (2n=32). Of these names, R. abortivus ssp. acrolasius and R. hyperboreus ssp. intertextus are combinations at a new taxonomical status, the latter plant long having been misidentified with the Altaian diploid R. natans.The size and morphology of the chromosomes were studied in considerable detail. Though the data are too limited to be conclusive for the grouping of the species of the collective genus, it is concluded that such observations are likely to be of considerable significance for the evolutionary revision of this large taxon into smaller and more natural groups.