Breeding systems of Australian Ranunculus in the alpine region

Abstract

The breeding systems of five species of Ranunculus that co-occur in the Australian alpine region were investigated in the field and glasshouse. Ranunculus muelleri, R. dissectifolius, R. graniticola, R. millanii and R. niphophilus are all facultatively xenogamous. Flowers appear to promote outcrossing by incomplete protogyny (flowers are female for 1-3 days, then bisexual for 3-10 days). Hand pollinations on plants in the field demonstrate that R. muelleri, R. graniticola, R. niphophilus and R. millanii are fully self-compatible, while R. dissectifolius is only partly self-compatible. However, low index of self-incompatibility values for R. graniticola indicate that this species may also be only partly self-compatible. Moderate levels of seed set from bagged flowers indicate that autogamous seed set due to automatic and/or possible thrips mediated intrafloral pollination may be common in all five species. Pollen/ovule ratios ranged from 992 to 3045 for these species of Ranunculus which are consistent with facultative xenogamy. The breeding systems of the Australian Ranunculus species in the alpine region are compared to that of other Ranunculus and examined in relation to the alpine environment.