Diversity in pollen grain characteristics and its importance in distinguishing Loranthaceae Juss. species grown in Saudi Arabia

Members of the Loranthaceae family are considered parasitic, and mistletoe negatively affects the growth and productivity of host trees. Loranthaceae has several complicated taxonomic issues. Six species of Loranthaceae grow naturally in Saudi Arabia, but these species have not been well studied. The aim of this work was to evaluate the importance of morpho-palynological characters as a taxonomic tool in the identification of Loranthaceae species growing in Saudi Arabia. The discriminatory power of these characteristics was evaluated using different statistical analysis methods. The descriptive characteristics of pollen polar and equatorial views and colpus type are useful for describing the species, and the presence of three colpus patterns was detected among the study samples: syn-(3)-, demisyn-(3)-, and zono-(3)-colpate. The quantitative characteristics, specifically, the equatorial diameter and P/E ratio, are the most useful and can be used to classify species within clusters based on their affiliation with genera, species, and subtribes Emelianthinae and Tapinanthinae. This study confirmed that pollen grain characteristics can be used as a taxonomical tool to identify Loranthaceae species. This information will aid in determining parasitic species that infect trees and could be useful for strengthening efforts in weed management.