It is a good idea to store supplies for difficult times. Did you know plants can do this too? In this lesson, we will examine the different types of tubers and how plants use them.

Plant Tubers Defined

Have you ever looked in your garden to see the changes that plants go through during the year? Plants go through complex cycles as the seasons change. Some plants live their lives to the fullest during spring, summer, and fall and die completely when winter comes. Other plants spend spring and summer growing and getting ready for fall and winter by storing nutrients to use during the difficult winter months.

A tool that plants use to store their nutrients and energy is the tuber. A tuber is a modified plant structure that is enlarged and used as a storage container for nutrients that would be difficult to obtain during dry periods and the winter months.

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Types of Plant Tubers

There are basically two types of tubers recognized by botanists: stem tubers and root tubers. Stem tubers form as thickened rhizomes or stolons. They normally form at the side of parent plants and are located near the surface of the soil. Stems grow out from the tubers on the top side, and roots grow from the bottom side of stem tubers. When stem tuber plants reproduce, the offspring grow from a root structure known as a rhizome. These plants store their food in the tubers of their offspring. The parent plant dies in the fall, and the nutrients in the tuber provide energy for the offspring to grow in the spring.

Root tubers are modified lateral roots that swell to form a storage organ. The enlarged area of the root may be one end of the root or the entire root of the plant. Plants with root tubers are perennials. This means they are able to survive off of the nutrients stored into their roots during the winter or dry period, and will regenerate during the spring. This is different from stem tuber plants that use their tubers to support offspring.

Examples of Plant Tubers

Common examples of plants with tubers include potatoes, cassava, and dahlias. Potatoes are one of the most commonly eaten foods on Earth. Did you know that when you bite into French fries or a baked potato, you are eating a stem tuber? Potatoes develop from enlarged stolons that have developed into storage organs. Potatoes have all the parts of a traditional stem, including nodes, internodes, and premature leaves. One initial cutting from a potato can be planted in the spring, and it will grow into a large plant. New potatoes grow off of the stem just below the surface of the soil and store nutrients so that each one can grow into a new plant during the following year.

Do you like to eat tapioca? It is derived from the cassava plant. Cassava is the third largest source of carbohydrates in the tropics. Cassava plants have root tubers. The root of the plant is modified into one large tuber that is used to store protein and carbohydrates in the form of starch.

Tubers are not only found in plants that we eat. Flowers use tubers as well to store energy and survive to the following year. An example of this is the magnificent dahlia. The dahlia is the national flower of Mexico and is known to be propagated from its tubers. Each plant grows multiple root tubers that it uses to store nutrients to survive through the winter, so it can begin to grow again the following spring.

Lesson Summary

Tubers are plant parts that are enlarged to form storage containers that the plants use to hold nutrients that allow them to feed their offspring or to survive through the winter. There are two basic types of tubers: root tubers and stem tubers. Common examples of tubers include potatoes, cassava, and dahlias.