"The student knows that organisms have structures that help them survive within their environments."
This is a recurring science standard for Texas students Kindergarten through 5th grade. Even the youngest students begin learning about plants, the structures and functions of their parts, and how those structures serve to help plants survive in their environment.
What is the purpose of a stem? Why would a rose have thorns? How does a vine climb up a wall? Why do dandelion seeds float on the wind? And why would a potato plant grow those delicious potatoes??
The answer, of course, is survival.
The potato, as students are often surprised to learn, is not actually a root but a tuber, a swollen part of a stem (rhizome) growing underground. The tuber is a storage unit of energy, in the form of starch, for the plant. Remove the green leafy part of the plant growing above ground (and its ability to make food through the process of photosynthesis) and the potatoes underground have enough energy stored to start the process of growing all over again. That is why potatoes are grown from "seed potatoes," which are really just potatoes that have been cut into smaller pieces where new stems will sprout from the nodes, or what we commonly refer to as the "eyes" of the potato. Yep, that is why old, wrinkly potatoes start to grow in your produce basket.
To better understand how tubers can help a potato in its unending quest for survival, let us consider another plant that has tarrorized gardeners across the United States: common Nutgrass or Nutsedge. This is a frustrating weed that, once growing where it is not wanted, is very difficult to remove. The reason? Nutgrass has a complex system of rhizomes and tubers, just like the common potato, that grow underground. Remove the top of the plant, but miss the swollen "nut" underground, and the plant has enough energy to grow a whole new plant. The nut, or tuber, in Nutgrass is also similar to the potato in that it is edible and actually has a pleasant, lightly sweet taste not too unlike that of jicima. It is not recommended that Nutgrass be consumed, however, unless it is well-known that the area has not been treated with chemicals.
At REAL School Gardens, we have modeled simple lessons that help teachers to recognize the learning that can be accomplished when students pull up Nutgrass in their school's garden or grow potatoes in their vegetable beds. Although a potato is better eaten, a Nutgrass specimen taped into a student's science journal serves as a memorable example of the important concept: "organisms have structures that help them survive within their environments."
So as students participating in Smart Potatoes continue to watch their plants grow this season, their learning is beginning to take root. Or, should we say, take tuber?
Take a look at this picture of Nutgrass. If you aren't familiar with it already, see if you can find some growing in your yard or landscaped bed. Dig deep to see if you can find its tuber - looks a lot like a mini potato!