Figure 6. A cross section of the stem of a
Wisteria sinensis (Leguminosae) stem. Note that the xylem vessels were
initially small in diameter (i.e., near the central pith), while this seedling
was self-supporting, but those produced later (i.e., nearer to the vascular
cambium and bark), while it was climbing, were much larger. Photograph by
Francis E. Putz.