Why potato or ginger is a under ground stem?

Potatoes and ginger are classified as underground stems because they develop from the stem of the plant rather than the root. In the case of potatoes, they are modified stems known as tubers, which store nutrients and energy for the plant. Ginger, on the other hand, is a rhizome, a type of underground stem that grows horizontally and also serves as a storage organ while producing new shoots. Both structures allow the plants to survive adverse conditions and propagate effectively.