What Exactly is a Tuber?

It might be a good idea to get to know what you're eating when you buy your veggies at the local farmer's market or grocery store, so you have the understanding of what you are eating. Technically speaking, a tuber isn't really a vegetable at all. Interestingly, the word tuber comes from the verb in Latin meaning to swell, tumere. Basically, the tuber is the part of the plant found under the ground that is engorged or swollen and is used by the plant to store food and nutrients. There are even two different kinds of tuber; the stem tuber and the root tuber. Potatoes belong to the stem tuber family because the potato itself is an extension of the stem that goes underground and the 'eyes' on the potato are actually additional buds which, if left alone, would produce new potatoes.

Tubers only last for one growing season, but if left in the ground past the growing season, new tubers will form from shoots growing off the original tuber the next year. Tubers are filled with starch, so a low carbohydrate diet would forbid the eating of tubers for this reason. Tubers such as potatoes also contain a compound known as the glycoalkaloid called solanine. Glycoalkaloids are poisonous and if the tuber isn't cooked, the glycoalkaloid could irritate the stomach and intestines. They tend to be bitter to the taste and have a burning sensation in the mouth. For this reason, it is very important to cook all tubers before eating. As an aside, tomatoes and eggplants also contain glycoalkaloids, although they are not tuber plants. Scientists are working on solutions to detect the levels of glycoalkaloids in potatoes, tomatoes and eggplant so that farmers will use only those plants with acceptable levels of glycoalkaloids, which is currently 20 milligrams per 100 grams of potato. This would make the crops more palatable and safe for consumers.

Root tubers are different from stem tubers because they actually grow on the root itself, not the stem. Root tubers, such as sweet potatoes, grow under the ground, like stem tubers, but can be found at the end of the root or even in the middle. They function the same as the stem tubers in that they also store nutrients and are used to keep the plant alive during the non-growing season. They are different from stem tubers also because they have the structure of roots and will have additional small fibrous roots coming from them that if left alone, will spread out underground and produce more roots and tubers. If you pull up a sweet potato from the ground, you will see the hairy looking new roots growing off the surface. Root tubers are designed to produce new plants when the growing season comes around again.