This photo of a cross section of the peduncle, is somewhat obscured as I made the cut with a saw after the whole thing toppled in the Fall. Looking more closely though shows a uniformity across it which suggests something about the rapidity of its growth as the meristem simply and quickly laid down one cell after the other in long fibers, vessels and trachea if a ground of parenchyma cells. There are no telltale rings or recognizable bodies, just a uniform ground.