INTERSPECIFIC HYBRIDIZATION AND ITS EVOLUTIONARY SIGNIFICANCE IN GENUS AQUILEGIA

Various hybrid combinations of 18 species and varieties of Aquilegia were produced, and several cross-pollinations were made which failed to produce hybrids. Pollen fertility of hybrids was generally high, with a total mean of approximately 50%, but highly variable among hybrid combinations and consistently lower than that of parental species. With the exception of frequent occurrence of giant pollen grains and rare synaptic failure of 1 or 2 homologous pairs, meiotic behavior in hybrid pollen mother cells appeared to be completely regular. Representatives of the Vulgaris Complex were observed to be intermediate genetically and morphologically leading to the interpretation of ancestral status among extant species. The greatest genetic diversity within the genus was shown to exist between A. ecalcarata and members of the Caerulea Complex.