Morphological differences between the flowers of Ramonda serbica, R. nathaliae and their hybrid

Abstract

Two species of the genus Ramonda from the Balkan Peninsula, R. nathaliae and R. serbica live together forming sympatric populations in only two localities in SE Serbia. In these populations natural hybridization between these two species has been detected employing chromosome number, genome size as well as pollen and seed analysis. It is very difficult to distinguish hybrid individuals from parents directly in the field on the basis of their morphological characters. Investigation of floral traits by traditional morphometry was carried out. The results showed the presence of clear morphological differences between R. nathaliae and R. serbica as well as pronounced similarity of hybrids with R. serbica. Our results showed that the most informative flower characters for distinction of hybrids from R. serbica and R. nathaliae are the colour of anthers and the angle formed by lines connecting the petal base and points of the maximal petal width. The complex cytogenetic structure of these populations detected in previous studies suggests a complicated and unpredictable character of inheritence in hybrid individuals.