Forensic potential of pollen grains: A case study from continental Croatia (town of Donja Stubica)

Background and Purpose: Pollen grains can come as “ invisible” traces during forensic palynological expertise. As forensic palynology is not carried out in Croatia at all, the main aims of our work were to establish an initial palynological collection for a limited area in Croatia and determine its forensic potential. Materials and Methods: For our case study, we chose a typical town from continental Croatia, Donja Stubica, in which there had been no previous floristic studies. The field survey was conducted during 2005, 2007, and 2021. Floristic and palynological analysis was carried out with an emphasis on the forensic potential of pollen grains. Results: A total of 141 representative plant taxa with pollen samples were collected. The taxonomic analysis showed that the area for the case study was chosen well. Palynological analysis showed that the highest number of taxa had pollen grains that were spheroidal in shape (60%), medium sized (70%), and colporate (41%). The pollen of the majority of taxa had excellent or very important forensic potential, due to their dispersal by insects (60%), a combination of two dispersal methods (23%), and autogamy (1%). In addition, due to the limited distribution of certain rare plants (e.g., Iris sibirica subsp. sibirica in Croatia), their pollen has an even greater forensic potential than the similar pollen of related, more widespread taxa. Conclusion: The generated palynological collection, due to the great forensic potential, could be used in the future as a comparative, and at least partly as a reference forensic collection, applicable in specific cases of legal pollen expertise in Croatia.