Wound-induced and naturally occurring regenerative differentiation of xylem in Zea mays L.

The regenerative differentiation of xylem, both around a wound in the stem and at the root junction was studied in seedlings of maize. The regeneration of vessels around a wound was very small, being limited to the very young internodes and sharply declining basipetally. There were more regenerative vessel elements and they differentiated faster above the wound than below it. The regenerative vessel elements around the wound were characterized by helical or annular pattern of secondary wall thickenings. Wounding also resulted in the development of additional vascular anastomoses in the leaf immediately above the wound, and in differentiation of discontinuous vessels in adjacent bundles. Regenerative vessel elements were very common where the adventitious roots connected with the stem internodes, and exhibited pitted or reticulated secondary wall thickenings.