ANATOMY OF BRANCH ABSCISSION IN LAGERSTROEMIA MICROCARPA WIGHT

Authors


SUMMARY

Some anatomical details of branch abscission in Lagerstroemia microcarpa Wight (Lythraceae) are discussed. Repeated abscission of numerous annual twigs and subsequent healing of their scars produce irregular growth of the subjacent branch portions to give gall-like structures. In the abscission zone, secondary xylem fibres are thin walled and poorly lignified, with dense protoplasmic contents and closely spaced septa. Disintegration of pith parenchyma cells and shrinkage of bark and wood tissues contribute towards weakening of abscission zone. The protective zone situated proximal to the abscission zone is strongly lignified and rich in extractives. Detachment occurs immediately above the protective zone leaving the encircling dormant buds intact. Abscission scars are healed centripetally by the usual method of callus formation from the cambial tissue. It appears that branch abscission in L. microcarpa is a mechanism to withstand drought by reducing the transpiring surface.

Ancillary