Abstract:In order to understand the phylogenetic relationship of Eucalyptus species common in China, the pollen morphology of 7 species was observed under scanning electron microscopy. The result showed that the 7 pollen characters of E. pellita and E. exserta were mostly in the top 2. Among 7 species, the equatorial length (EL), width (EW) and area of E. pellita pollen were the largest with 17.522, 17.090 μm and 300.830 μm2, respectively; the colpus length (CL), width (CW) and size of E. exserta pollen were the largest with 6.576, 0.720 μm and 4.718 μm2, respectively; and the equatorial area of E. camaldulensis pollen was the smallest, colpus size of E. wetarensis pollen was the smallest. According to cluster analysis based on pollen characters, 7 Eucalyptus species could be divided into 3 groups under 87.5% of information remaining, including E. pellita and E. exserta, E. wetarensis and E. grandis, and the others. The pollen wall ornamentation of E. pellita and E. exserta were smooth, which E. tereticornis and E. camaldulensis was conventional, and that of E. urophylla, E. wetarensis and E. grandis was rough. From pollen morphology analysis, the phylogenetic relationship between E. pellita and E. exserta was closer, which between E. wetarensis and E. urophylla was farther, and that among E. tereticornis, E. camaldulensis and E. grandiswas consistent with traditional classification. Therefore, there were new interspecies relationships among Eucalyptus species from pollen morphology, which had guiding significance to the hybridization breeding of Eucalyptus.