MICROMORPHOLOGICAL CHARACTERISTICS OF POLLEN GRAINS OF RUELLIA L. (ACANTHACEAE) IN SAUDI ARABIA

This paper aims to provide an accurate morphological description of pollen grains of Ruellia L. (Acanthaceae), which is widely spread in Saudi Arabia, as a first study in the region. Eight species of Ruellia, Ruellia sp. Abha (Ruellia brittoniana), tweediana.white) were collected from the western and southwestern regions of Saudi Arabia for microscopic characterization using a light microscope and scanning electron microscopy. The size and shape of the grains were recorded, as well as the number of apertures and pollen wall sculpture, in addition to a genus key based on pollen characteristics. The results showed that in all studied species pollen were large, and the sculpturing was reticulate in each, but there were some differences in other parameters which divided the species into two groups according to the number of apertures, the grain genral shape, granules in the tectum layer, and lumina cavity size and shape in each species.