We all consume lots of vegetables that grow underground, but do we know the difference between tubers, bulbs, roots and rhyzomes? Let’s find out!

Tubers: Potatoes are the best example to understand the characteristics of this class. Tubers have an irregular shape and their size usually varies between 3 and 6 cm. They have an outer “skin” that protects the inner part, which is usually lighter in colour. They sometimes feature outgrowths (known as “eyes”) from which new plants develop. Once these buds reach their maximum size, they don’t propagate.

Bulbs: Bulbs vary in shape, with some more elongated and others rounder. The best-known bulb is surely the onion. Unlike tubers, bulbs don’t have a skin but rather a thin outermost layer. The fleshy layers of the onion are called “tunicae” and every bulb contains several, which develop concentrically around the bud. Although many types of bulb exist, all of them present a narrowing of the upper part (from which the leaves sprout) and of the lower one (where the various layers join). Bulbs renew themselves for the plant’s entire life cycle, with outer layers being replaced by the ones beneath them.
Roots: Roots, which include carrots, beets and turnips, are also commonly used for food. Their shape is either cylindrical or roundish, and tends to taper downwards. While tubers mainly contain carbohydrates (which, in the form of starches, supply the body with energy), roots are a good source of water and minerals.
Rhyzomes: This family includes turmeric and ginger, which are used in many common spices. Rhyzomes are similar to roots and have a cylindrical shape, elongated and swollen, but usually develop horizontally. Like bulbs, they are self-regenerating, growing at the front end while decaying at the back one.

Do you have green fingers? Learn how to grow potatoes at home.