Abstract: Pollen morphology of 6 species, 1 variety, 1 form of genera Rhododendron (Ericaceae), distributing in northeast of China, was examined in the light microscope(LM) and with the scanning electron microscope(SEM). All of the pollen grains of Rhododendron are characterized in tetrahedral tetrad. Pollen grains of Rhododendron are spheroidal or subspheroidal with 3-colporates, which shaped as half-colpi due to two neighborly grains of tetrahedral tetrad link together. Exine is composed with two layers in LM. The ornamentation of the exine is reticulate or granulate. The size of the pollen grains ranges from 34.7~61.7μm. Pollen grains are diverse in size and in the ornamentation of the exine. These can be taken as the characters for identification of species.

Key words: Rhododendron, Pollen morphology, Tetrad