Throughout history, they've been alternately maligned as food fit only for animals and revered as "apples of life." They're down and dirty and terrible unassuming, yet these often misunderstood vegetables kept Incan civilizations thriving, helped fuel the Industrial Revolution, triggered mass population shifts, and are now one of the world's four most important food corps. They are also used to produce paper, adhesive, biodegradable plastics, and even cosmetics. These humble tubers -- potatoes -- can provide an exciting focus for scientific investigations, nutritional lessons, and for exploring world cultures and history.
Spuds, Up Close
It may be winter, but your classroom gardeners don't have to be a bunch of couch potatoes. Have each student bring in a potato, then have pairs or small groups of students observe the tubers, writing down all of the observations they can make as well as things they know about potatoes. Make a class chart with the headings: Things We Know About Potatoes and Things We'd Like to Know. (At the end of your potato adventures, you may want to add columns What We Learned and Questions we Still Have.) Refer to this chart throughout your potato unit and at the end to assess what students have gained. Also, consider referring to page 148 in GrowLab: Activities for Growing Minds for an introductory potato "trivia" activity.
Invite your students to closely examine a potato. They should discover that it has numerous small indentations or "eyes" (and even eyebrows!). These are actually the beginnings of tiny buds which, under the right conditions, will produce sprouts. Most farmers and gardeners plant pieces of potatoes with eyes (called "seed pieces") instead of growing potatoes from actual seeds. When a piece of potato is planted, the starch in this seed piece "feeds" the plant until it's leaves are mature enough to photosynthesize and produce their own nutrients. The nutrients in the seed piece are used up in the process.
If you did up a young potato plant, you'lll find stems and leaves emerging from the potato sprouts and thread-like roots growing from their base. Compound potato leaves (made-up of small leaflets) will eventually be arranged around the stem in a spiral pattern -- an adaptation to ensure that each leaf receives as much sun as possible, without shading the others.
Potato plants also have underground stem extensions, or rhizomes. Once the plant has finished its initial phase of growth, the leaves make more carbohydrates than are necessary for plant growth, and the extra are stored as starch in the rhizomes. As this starch builds up, the tips swell (usually about five to seven weeks after planting) into the tubers we call potatoes. Although potato plants do produce flowers which, when pollinated, produce seeds and small fruits, these are not part of our diet. If you have the opportunity, try comparing potato flowers with those of their relatives-tomatoes, eggplant, peppers, petunias, tobacco -- and see if you notice a family resemblance!
The Tubers that Changed History
Ancestors of the Incas living high in the Andes in South America more than 6,000 years ago are believed to have stumbled on many types of small, bitter wild potatoes that survived well in the harsh mountain climate. These early farmers developed sophisticated growing methods, allowing them to cultivate huge quantities of potatoes. To keep their precious harvest from spoiling, they spread potatoes on the ground until they froze overnight, then walked on the potatoes the following day to squeeze out the water. After letting them dry in the sun and repeating this for several days, they had a dried powder called chuno -- the first freeze-dried product!
When Spanish explorers came to Peru in the 1500s looking for gold and silver, they paid little attention to these homely tubers, and the few potatoes that they did take back to Europe wee not an immediate hit. Many people were skeptical, since this strange new food that grew underground wasn't even mentioned in the Bible! It didn't help matters when Queen Elizabeth's cooks threw out tubers and cooked the leaves and stems, promptly making the royal guests ill!
As food fads, superstitions, and social class perspectives shifted, potatoes were at times considered as peasant food barely fit for human consumption and at other times reserved as a delicacy for the wealthy class! Easy to grow in many climates and soils, potatoes had by the mid-1800s become one of Europe's most important foods. The poor masses finally had a crop that was easy to grow and process, was very nutritious, and could be raised on small plots. Nourished on potatoes, more children survived than were needed to help on farms, and as more people moved to cities to work in factories (earning income to spend on more goods), the Industrial Revolution thrived.