The morphological structure of the inner wall of the vessel elements in 14 species of Maloideae (Rosaceae) from Heilongjiang Province was studied by means of scanning electronic microscope (SEM).The result showed that:(1)The length,the width and the slope of vessel elements are various in different species;(2)All studied species have pitted vessel type,while reticulated and spiral vessel only appear in the Malus and Sorbus;(3)Helical thickening of the inner wall of the vessel elements occurs in most species except in Malus and in Crataegus maximowiczii and C.sanguinea;(4)The arrangement of pits is alternate,opposite or both in one element;(5)Simple and scalariform perforations were found on the end wall of the vessel elements in Sorbus pohuashanensis,Malus baccata and Crataegus pinnatifida var.psilosa,while other species only with simple perforations on the end wall of the vessel elements;(6)The remnants of pit membrane are common in all species.These results indicated that the morphological structure of the inner wall of the vessel elements is systematic significance for Malodieae,and the micro structure of the vessel elements is also adapted to their environment.