Abnormal increase in size of plant organ due to the increase in the number of cells is called as

An abnormal increase in the size of plant organs due to the increase in the number of cells is called Hyperplasia.
It is an enlargement of an organ or tissue caused by an increase in the amount of organic tissue that results from cell proliferation.
Hyperplasia may be due to any number of causes, including the proliferation of the basal layer of the epidermis.