The roots.
corm
Underground Stem
The part of the potato plant we eat is called the tuber, which is actually an enlarged underground stem.
Rhizome is an underground stem that possesses vascular tissues. These tissues aid in the transport of water, minerals, and nutrients throughout the plant.
Potatoes are considered stems and not roots, because they are the part of the stem of the plant that grows underground, it's the part of the stem that thickens and accumulate starch.
poi
Yes, water chestnut is an aquatic plant that grows in shallow water, and its edible part is an underground stem known as a corm. The corm is a bulb-like structure that stores nutrients for the plant's growth and propagation.
Ginger (Zingiber officinale) is from the root or underground stem (rhizome).
ginger is called an underground stem or a rhizome because it looks and acts like a root but it is different from a root because it usually grows horizontally. Rhizomes usually produce aerial stems and underground roots from these buds.
It gets its roots from the underground stem of its parent plant.
Underground stem or root
The rhizome is a creeping underground stem of some plants. A rhizome is thick and swollen and acts as a food store. Iris is an example of a rhizomatous plant.