Morphological Structure Of Vessel Elements Of Maloideae From Heilongjiang, China

The morphological structure of the inner wall of the vessel elements in fourteen 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,the length of vessel elements are between 263.87 and 436.97μm,changes relatively greatly,the longest of which is C. maximowiczii,the shortest is C. pinnatifida; the width of vessel elements are between17.27 and 27.30μm,changing scale are small,The widest is C. dahurica,the most narrow is C. Melanocarpus;the slope of vessel molecules are between 45.25°and 61.79°,changing scale are small,the biggest is C. maximowiczii,the smallest is C. sanguinea.(2) The type of vessel is pitted, reticulate, spiral. All studied species have pitted vessel type, while reticulated and spiral vessel only appear in the Malus and Sorbus.(3) The inner wall of the vessel elements have helical thickening. It 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. alternate, opposite appear in the subfamily nearly half plants,both in one element only appear in the S.Pohuashanensis var.amurensis and Cotoneaster B.; the remnants of pit membrane are common in all species.(5) Type of perforation plates: simple, scalariform, 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.The morphological structure of the inner wall of the vessel elements are of systematic significance for Malodieae, and the micro structure of the vessel elements is also adapted to their environment to some extends.