Abstract: We observed pollen morphology of 11 Malus species ornamental crabapple cultivars by scanning electron microscope, and studied the relationships and groups by average (UPGMA) cluster analysis method according to the pollen shapes, ornamentation strips and hole-frequency. All of the 11 varieties’ pollen shapes in side view were oblongoval, and in polar view triangular or nearly round, which belonged to the N3P4C5 type pollen. The exine surface was covered with strips. There were significant variations among varieties in pollen shape, strips shape, decoration, and pore patterns. By UPGMA cluster analysis, 11 cultivars could be classified into three groups at similarity distance 3.30 level. ‘Hongshuang’, ‘Hongsha’ and ‘Hongbo’ could fall into the first group as the three varieties with long pollen stripe bundle’s branch, and sparse and regular ridge. ‘Hongfen’, ‘Hongliang’, ‘Xuelai’, ‘Xueqiu’, ‘Hongyan’ and ‘Xueqian’ could fall into the second category with sparse ridges, parallel to overall pollen, little sub-fork, and medium pore frequency. ‘Dorge’ and ‘Xuekai’ were in the third group with irregular ridges, smallest pollen grains and smaller pore diameter, and they were located in the top of evolution.

Key words: crabapple, scanning electron-microscope(SEM), pollen morphology, ornamentation strips