Pollen grain analysis of some selected Maltese medicinal plants

Abstract

Palynology is the study of the pollen grains and spores in different fields of study. Sample collection was carried out throughout the Maltese Islands, mainly in four specific areas - Zone 1, which was Targa Gap Gardens in Mosta, Zone 2, Ghammieri Government Farm in Marsa, Zone 3 Argotti Botanical Garden in Floriana and Zone 4 which was a House Garden in Rabat, Malta. Pollen grain samples were collected from 10 medicinal species and then stained with Calberla's stain to facilitate the characterization of the pollen morphology, including size, shape and pores. The pollen grains were visualized under the microscope for quantitative (low power) and qualitative (high power) characteristics. The pollen grain size varied between 37.8µm for Reseda alba L. and 122.6µm for Urtica urens L. Pollen grain shape varied from spherical (Anthemis nobilis, Citrus limon, Papaver somniferum and Reseda alba), spherical with bladders ( Lavandula multifida, Rosmarinus officinalis and Urtica urens), triangular shaped (Prunus armeniaca and Prunus persica) to wedge-shaped (Aloe vera). The pollen grains proved to be all porate, but with a different shape and number with different pollen species. From the results it could be concluded that different plant species bear pollen grains of different shapes and sizes. Also, the pollen may bear a number of pores that are important in the identification of pollen grains. This study showed how pollen characterization may be utilized as a partial characterization of plant source.