Abstract:The occurrence and morphology of tyloses and gums in vessels of 102Chinese hardwood were investigated using SEM.Tyloses were present in 49species and gums in 12 species.Morphological types of tyloses are:foamed,ladder-,collasped-shaped,globular.Morphological types of gums are:vesselsocclusied,thin layer,small droplet.The mean values of length and widthpit aperture of vessel to parenchyma pit were greater than 3 and 2μm,respectively,in species having tyloses and were less than these values in species having gums.The obeservation of ultrathin section of Robinia pseudoacacia wood by TEM showed:the tyloses walls has a compound middle lamellaand primacy walls with simple pits.There are more tyloses and gums invessele of pith of 3 species.The content of tyloses and gums decreased invessels of each growth ring from pith to bark.