Is the blue zinc violet (Viola guestphalica Nauenb.) A taxon of hybrid origin? Evidence from embryology

摘要

Investigations of reproductive processes of the blue zinc violet (Viola guestphalica Nauenb.) from its natural location in Germany (Blankenrode) and from two sites of introduction in Poland (Welnowiec zinc spoil and a private garden in Sosnowiec-Ostrowy Gornieze) showed significant disturbances resulting in reduced plant fertility. Pollen viability estimated by acetocarmine staining was relatively low, with 54% viable pollen grains in plants from Welnowiec and 62% from the garden. Specimens from Blankenrode had 80% viable pollen but the pollen grains differed in size conspicuously. Giant abnormal pollen grains accompanied very small ones. Necrosis affected anthers and pistils, including degeneration of whole anthers and ovules, whole embryo sacs or embryo sac elements, and abortion of embryos. The pathway of female gametophyte and embryo development was normal in 61% of the ovules. Necrosis of somatic tissues and generative cells at different developmental stages was found in 28% of the ovules, and irregular development in 11% of them. As a consequence, embryo viability was reduced to 33%. Embryological data indicated that V. guestphalica is not a well-stabilized genotype. The possible origin of the blue zinc violet is discussed.