Fig. 15.3-3. Transverse section of wood of ash (Fraxinus). Whereas the cells in conifer wood are deposited in regular radial rows, the rows of cells in dicot wood are disrupted as the young vessel element precursor cells swell to their full width, pushing neighboring cells apart. Here in this Fraxinus wood, the enlargement of the vessels has distorted even the rays. Remember that each of these vessel elements started out as a cell just as small as the fiber cells making up the bulk of the wood, so each underwent tremendous enlargement. Despite being pushed around by the vessels, the ray cells undergo proper morphogenesis and then function normally.
The very wide vessels are earlywood vessels, aligned at the boundary with the latewood of the previous year. This is a ring porous wood.