Aim and background. The genus Onobrychis Adans (Fabacea) belongs to Hedysareae tribe. Onobrychis is the biggest genus of Hedysareae Tribe which has 27 endemic species in Iran.

Materials and Methods. Pollen morphology of 11 taxa of the Onobrychis was studied with Scanning Electron Microscopy (SEM).

Results. the results obtained showed that pollen grain is 3-collpate, prolate or perprolate. Exine ornamentation is reticulate and dimention of lumen is different. The equatorial view was elongated, elliptic and the pollar view was circular or obtus-triangular. One pollen type is recognized based on size, equatorial and polar view and exines ornamentation.

Conclusion. Pollen morphological studies provided the opportunity to identify and separate species.