Floral characteristics and gametophyte development of Anemone coronaria L. and Ranunculus asiaticus L. (Ranunculaceae)

Anemone coronaria and Ranunculus asiaticus both belong to the Ranunculaceae, a large plant family with many ornamentals of horticultural importance. In this study, the floral characteristics and the development of reproductive structures of these two cut flowers are investigated. On a macro-level, flower morphology was analysed by dissections, light microscopy and scanning electron microscopy (SEM). The female and male gametophyte development as well as embryogenesis was investigated on a micro-level by light microscopy of paraffin sections and fluorescence microscopy. These analyses confirmed that anthers of A. coronaria and R. asiaticus are tetrasporangiate and that the stamens of R. asiaticus can be transformed to petals. Pollen development in A. coronaria and R. asiaticus is of the simultaneous type. The mature pollen is spheroid, polyporate and bicellular. For both species, the development of the embryo sac is of the octonucleate Polygonum-type. The two polar nuclei inside the embryo sac fuse before fertilization while two of the three antipodal cells persist after fertilization. On the moment of fruitier shedding, the embryos are not fully developed yet implicating an autonomous maturation prior to germination. Finally, pollination tests revealed that R. asiaticus `Alfa' is self-incompatible. The results presented here provide new insights in the reproductive biology of A. coronaria and R. asiaticus supportive for future breeding strategies.