To reveal the material basis of Phyllostachys edulis ‘Pachyloen’ fast growth, and to further explore the mechanisms of fast growth of Ph. edulis ‘Pachyloen’, we used paraffin sections combined with optical microscopy techniques to study the temporal and spatial dynamics of starch granules in bamboo culms during the elongation growth of Ph. edulis ‘Pachyloen’. The results showed that: (1) the content of starch granules gradually decreased during the elongation growth of bamboo culms. In individual internodes, the content of starch granules varied from site to site. In the axial direction, the content of starch granules from top to bottom in the same internode increased, and the highest was at the base of the internode. The content of starch granules in nodes was always higher than that in internodes. After the elongation growth ceased, there were still starch granules in the long and short parenchyma cells. (2) In the radial direction, the starch granules gradually decreased from the outside to the inside, and there were obviously more starch granules around the vascular bundle than in other parts. (3) Abnormal diaphragm led more starch granules in the culms and similar content of starch granules in each part of the internodes. The temporal and spatial dynamics of starch granules are consistent with the development of internode cells during the growth of Ph. edulis ‘Pachyloen’, and the nodes might regulate the elongation growth of bamboo mainly by controlling material transportation.