Morphological characterization of some gymnosperm non-saccate pollen grains.

The gymnosperms are a taxon of plants that release large amounts of pollen. Some genera of this group are specifically studied because their pollen is known to be the cause of respiratory diseases. The medical interest in allergenic bioaerosol has led to the need for daily aerobiological monitoring. The technique applied involves the use of an instrument that aspirates a volume of air corresponding to human inhalation and the identification under the light microscope of the allergenic bio-particulate present. Morphology alone does not allow to distinguish the non-saccate pollen thus they are attributed to a single category, i.e., Cupressaceae-Taxaceae, without distinction between genera belonging to the different families. This research represents an attempt to overcome the difficulties in the recognition of non-saccate gymnosperm pollen. Twenty-one species belonging to the Araucariaceae, Cupressaceae, and Taxaceae families were selected in Perugia (Umbria, central Italy). The most common species and other less widespread ones were selected, all characterized by non-saccate pollen. The results obtained allowed us to identify four morphologies: aperturoidate, areolate-papillate, areolate-porate, and porate. This study provides further knowledge regarding the morphological characteristics of these pollen grains, in order to overcome the general definition of inaperturates attributed to the pollen of some gymnosperms. [ABSTRACT FROM AUTHOR]