Explanation:

The edible part of the potato is tuber (modified stem), not root. Stem, in botany, the plant axis that bears buds and shoots with leaves and, at its basal end, roots. The stem conducts water, minerals, and food to other parts of the plant; it may also store food, and green stems themselves produce food. There are four types of herbaceous stems. These are climbers, bulbs, tubers and runners. A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold leaves, flowers, cones, axillary buds, or other stems etc. ... In most plants, stems are above the soil surface but some plants have underground stems called stolons or rhizomes.