Contribution à une étude palynologique de trois espèces de Rosacées (tribu des Pyrées) indigènes au Liban: Pyrus syriaca Boiss., Crataegus azarolus L., C. monogyna Jacq.

Abstract In Lebanon, three Rosaceae from Pyreae tribe are commonly cultivated: Pyrus syriaca Boiss., Crataegus azarolus L., C. monogyna Jacq. Four samples were taken on the flowers of three species to study the pollinic morphology with light and scanning electron microscope. The morphologic observation and the numerical treatment of various types of characters were realised to determinate the morphology of pollen grains, the stereostructure of the tectum, and the variations of dimensions (average, minimum, maximum values) of the polar axis and of the equatorial diameter in order to highlight the precedent descriptions and to explicit the pollinic morphology of the three species. The differences between Pyrus syriaca and two Crataegus are easy. The fine pollinic morphology of both Crataegus is compared and a biometric analysis is necessary to show the specific pollinic dimensions witch differentiate the both species.