Pollen morphology of some onosma species (Boraginaceae) from Turkey

The pollen morphology of nine taxa three of which are endemics belonging to onosma l. (boraginaceae); o. orientale,o. halophilum,o. bourgaei,o. chlorotrichum,o. heterophyllum,o. ambigens,o. oreodoxum,o. sintenisii and o. bulbotrichum from turkey has been investigated by light microscopy and scanning electron microscopy. the shape of pollen grains of onosma is frequently prolate,subprolate and sphaeroidea. the outline in polar view is subrounded and subtriangular. the dimension for the polar length ranges between 13.01-21.57 μm,equatorial width 10.56-20.30 μm,colpi length 8.19-16.58 μm,colpi width 1.69-4.36 μm,pori length 1.05-4.28 μm and pori width 2.52-10.71 μm. the pollen morphology of studied taxa are taxonomically of significant characters. the main pollen morphology differences have been found at the section level,especially in pollen type.