Root vegetables are underground plant parts eaten by humans as food. In agricultural and culinary terminology, the term applies to true roots such as taproots and tuberous roots as well as non-roots such as bulbs, corms, rhizomes, and stem tubers.

A storage organ is a part of a plant specifically modified for storage of energy (generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have an underground storage organ are called geophytes in the Raunkiær plant life-form classification system. Storage organs often, but not always, act as perennating organs which enable plants to survive adverse conditions.