Pollen Morphology and Pollen Production of Invasive and Native Impatiens Species Growing in Bulgaria

The purpose of this study was to establish baseline data concerning certain aspects of pollen biology of the invasive alien species Impatiens balfourii and I. glandulifera, and the native I. noli-tangere to the flora of Lozenska Mt. The aims of this study were: 1. To evaluate variation in pollen morphology, pollen production and fertility/sterility in the populations of I. glandulifera in order to obtain data for its invasive success and compare with the other two species; 2. To analyze differences in pollen biology in two flower color forms (pink and violet). The pollen morphology was investigated with light microscope and the pollen grains are 4(5)-zonocolpate oblate or peroblate in equatorial view, and rectangular-obtuse or suborbicular in most 4-zonocolpate grains in polar view, with a reticulate ornamentation. The mean pollen production per flower and stamen was very high in all three species comparable with anemophilous plants. The sterile pollen was between 8.9% and 17.54%. The variations in pollen biology can be related to different evolutionary adaptations of the flowers to be more attractive for pollinators and successful in reproduction and distribution. The results are of importance for taking measures to reduce the invasiveness of these alien species.