Abstract: The present paper deals with studies of the pollen morphology of the tribe Trigonotideae (Boragidaceac-Boraginoi-deae), containing five genera, i. e. Trigonotis, Brachybotrys, Sinojohnstonia, Omphalotrigonotis and Mertensia. The pollen grains of 26 species belonging to these genera respectively were examined with the light microscope and scanning electron microscope. The pollen morphology of the genera in question is distinctly different between each other and may furnish valuable characters for distinguishing them and for supporting the establishment of the new genus, Omphalotrigonotis, An analytical key to the pollen grains of the five genere is as follows:1. Pollen grains dumbbellform in equatorial view, more or less constricted in equatorial region, tricolporate and tripseudocolpate. 2. Pollen grains the smallest in the tribe Trigonotideae. exine almost psilate…………………………Trigonotis Stey. 2. Pollen grains larger, exine with ornamentations. 3. Exine foveolate…………………………Sinojohnstonia Hu 3. Exine fillely granulate or spinulate. 4. Exine finely granulate…………………………Mertensia Roth. 4. Exine spinulate…………………………Blachybotrys Maxim. ex Oliv. 1. Pollen grains rhombic in equatorial view and not constricuted in equatorial region, tricolporate, not pseudocolpate. exine finely reticulate…………………………Omphalotrigonotis W. T. Wang.