POLLEN MORPHOLOGY OF THE GENUS ROSA L. (ROSACEAE) IN IRAN

Pollen grains of 13 species of the genus Rosa belonging to two subgenera, Rosa and Hulthemia, and one hybrid species were performed using light (LM) and scanning electron microscopy (SEM). The basic shape of pollen grains in 11 studied taxa is subprolate but prolate and rarely prolate- spheroidal pollen grains also can be found in nine species. The grains are usually trizonocolporate, aperture structure consists of 3 ectocolpi and 3 endopores. Endopores are located in the middle part of ectocolpi. Similar to the other genera of Rosaceae, striate sculpturing is the main ornamentation of pollen grains. According to surface sculpturing features such as slope, diameter and distance between ridges, number and size of perforations is classified into four major types and four subordinate types; however, other ornamentation types such as gemmate are observed. Characters of pollen grain provide useful criteria for separating taxa in sectional and specific levels.