Pollen biology of the serpentine-endemic Orobanche nowackiana (Orobanchaceae) from Albania

The holoparasite flowering plant Orobanche nowackiana Markgr. is a rare endemic plant that parasitises the Ni hyperaccumulator species Alyssum murale Waldst. and Kit. in Komjan Mt. (Albania). The purpose of this study was to establish baseline data concerning aspects of its pollen biology. To achieve this goal three objectives were addressed: (1) describe pollen morphology; (2) study pollen production and fertility/sterility; (3) study the localisation of metals in anthers and pollen. Pollen morphology was investigated with light microscope and scanning electron microscope (SEM) observations. The pollen grains are 3-colpate, most often oblate-spheroidal, with long colpi reaching the poles. The ornamentation is microreticulate. The anther and pollen grains were micromorphologically analysed by SEM coupled with an energy-dispersive X-ray probe (SEM-EDX). Low concentration of Ni was recorded for anthers (0.38%) and pollen (0.1–5.6%). Variation in pollen production was found for the flowers of the same individual. The mean pollen production per flower and stamen was 59 365 and 14 938 pollen grains respectively. The sterile pollen was above the limit considered as a normal abortion and was between 10.1 and 38.0%. From a palynological point of view our results are important for taxonomy and support keeping the species in the genus Phelipanche.