Cellular totipotency was demonstrated by

Cellular totipotency was demonstrated by F. C. Steward.
Cellular totipotency is the inherent potentiality of a plant cell to give rise to a whole plant, a capacity that is retained even after a cell has undergone final differentiation in the plant body.
The more cell types a cell can differentiate into, the greater its potency. Steward conducted experiments on carrot root tissues and was the first to demonstrate totipotency.