Abstract: The classification of bamboos is often difficult, because they do not bloom regularly and variation of their vegetative organs occurs easily. This paper deals mainly with the dissection of the culms at the base, middle, and top of 31 species from 10 genera of caespitose bamboos cultivated in South China. Proceeding from the exterior to the interior, observations were made on the sections of the parts mentioned above, and according to differences noted in structure, size, shape, and arrangement of the vascular bundles, a division into 4 vascular bundle types was arrived at and a key for 31 species complied in an attempt to base the classification of bamboos on the structure of the vascular bundles.