Trunks of some of the aged tree species appear to be composed of several fused trunks. Is it a physiological or anatomical abnormality ? Explain in detail.

$\Rightarrow$ It is internal structural irregularity. It is an irregular type of secondary growth where regular fascicular cambium or cork cambium does not occur under normal conditions. In case of old tree barks irregular secondary growth is produced by cortex and pith vascular bundles.

$\Rightarrow$ Hence extra or subsidiary vascular bundles produce appearance such that it occurred by combination of many barks.