Tangential view of locust cambium & derivatives

In this tangential sectional view of black locust (Robinia pseudo-acacia) stem, is shown the vascular cambium. Only in this view is it easily determined that the cambium is storied (i.e. stratified), and that the ray initials are organized into multicellular, multiseriate units.

It should be noted that storied cambium does not necessarily give rise to storied wood or rays. The intrusive growth of the fusiform initials is clearly observed and penetrates through existing rays.

Note the tapered end walls of the fusiform initials, and sites (to the right) where some have cross-walls internally that segment the cells into much smaller initials that will become rays.