Investigating Tallgrass Prairie Plants
OverviewBy growing and comparing plants, students discover how prairie plants differ from other plants and how prairie plants and the environment benefit from these differences.
Students will be able to:
- Compare and contrast prairie plants with other plants.
- Explain how prairie plants' unique characteristics help them survive in a prairie environment where other plants do not.
- Explain how prairie plants' adaptations could provide benefits to the environment.
- Create experiments to answer questions, like: Do prairie plants' root systems allow them to absorb water differently or resist drought longer? Can they withstand temperature extremes better than other plants? How well do their roots anchor them compared to other plants?
- Draw a conclusion that makes sense of their observations and data.
The growing point of many prairie plants is underground where it can survive fire and drought and still regrow. Prairie plants have roots that extend far down into the ground (as much as 3.5 meters) and the roots form networks to absorb moisture during dry periods. The prairie plants create more roots each year and some of the roots die each year, adding nutrients to the soil. If the prairie plants' roots can't find enough moisture for the plant to keep growing, the part of the plant above ground turns brown and dies off, but the root system and growing point remain alive underground. Prairie plants commonly have narrow leaves that lose far less water to evaporation than broad, flat leaves. They also produce brightly colored flowers that attract pollinators such as bees, wasps and birds.
If feasible, students may plant a common shallow-rooted plant such as Kentucky bluegrass and a longer network-rooted prairie plant such as big bluestem, little bluestem, or Indian grass in two separate coffee cans or in a glass container or old fish tank. Plants will need to grow for a month or two. Alternatively, you may purchase already growing plants or obtain pictures of these plants. Students may also visit a prairie to observe the plants.
Ask students "How are prairie plants different from other plants?" and "How do these differences help the plants survive adverse conditions such as those found on the prairie?" Students must determine how they can answer these questions when provided with the plants or the pictures. Students may also visit a prairie to observe the prairie plants and compare them to plants in their own yards. Students may want to do some research after they have observed the plants. Students should observe the differences in the plants' roots (if visiting a prairie, do not dig up plants, use pictures of root systems instead), stems and leaves (and flowers if they have them).
If provided with plants to use in experiments, students should compare and contrast their ability to absorb water by pouring the same amount of water on both and see how fast it is absorbed or how much drains through. Students should also test how well they tolerate dryness by not watering them and seeing how long it takes them to wilt. (Wilting will not hurt the plant as long as you water it well before it turns brown or loses leaves.) Students could also see which one tolerates cold or warm temperatures better by placing them in a very warm place or in the refrigerator or even the freezer for a given amount of time (this may kill them so do this at the end). Students could see which one holds soil better by trying to remove them from the soil (this may damage plant) or planting them on a slope and pouring large amounts of water on the slope above them. These investigations should take 2 or 3 days and can be done as a class or in groups of 2 or 3 if you have several of the plants.
Students present their findings in a report, a power point, or even a slide show. If students present to the whole class, this may take 2 or 3 days.
Students should describe the longer roots in a prairie plant along with the fact that prairie plants' roots branch more. This allows them to absorb more water. Students should have observed the narrower leaves on the prairie plant that reduce their water loss as well and allow them to survive dryer conditions. Students may also have noticed the prairie plants hold soil better than other plants, absorb water better than other plants and resist temperature extremes better. Students may have found (probably by researching) that the growing point of prairie plants is under the soil, while in other plants it is above ground and this is one way they survive adverse conditions better. Reports should be 3 to 4 pages, double spaced, citing the students observations and research, as well as any data from their investigations and what they concluded from the data. Power points and slide shows should be about 15-20 slides containing the same information as in the report.
Park ConnectionsThe prairie is part of Iowa's natural environment. Farmers had plowed most of the prairie for farmland by the time Herbert Hoover was born. The park's reconstructed grassland maintains the rural open spaces that young Herbert Hoover knew. The native plants' deep root systems hold soil in place against erosion by water and wind, and absorb water that would otherwise quickly run off and contribute to flooding.
Students can continue investigating how prairie plants can be effective methods of flood control as well as erosion control. Not only do prairie plants absorb a lot of water with their deep and branching root systems, these roots also hold soil in place against wind and water erosion.