Teaching kids about science and seed dispersal
Plants can’t move on their own, so how do plants grow all over? Help youth understand the science behind seed dispersal.
Unlike animals, plants can’t move on their own. As a result, plants have evolved a variety of adaptations for seeds to spread out and away from their parent. Why would it be important for offspring to move away from the parent? Think about children and their parents racing to get the last slice of pizza or cookie from the package: close proximity means that parents and offspring need to compete for food, sunlight and other resources. To help children learn more about seeds and their dispersal mechanisms, try some of the experiments and questions below.
- Floating or flying seeds. Many seeds, like dandelions, cottonwoods, milkweed and cattail are light and have adaptations that allow them to be easily carried by the wind. Do any of the seeds have a “better” design than others? Place several different seeds under a box on a table in front of a fan: turn on the fan and then lift the box. Note how far the different seeds fly. Do they fly in a straight line? What seeds fly the farthest distances? Why?
- Seeds with wings. Maple, box elder and elm “helicopters” also disperse seeds away from the parent plant. Conduct some experiments by dropping these seeds from a height, such as in a stairwell, and see where the seeds land in relation to where they were dropped. Do they spread out?
- Sticky seeds. Many seeds have Velcro-like adaptations that enable them to stick to fur and clothes. Find burrs and look at them under a magnifying glass. Compare the structure to Velcro shoes: how are they alike, and how are they different? A fun experiment is to have children walk through a field in old socks and see how many seeds stick to their socks. Then put the socks in some soil and water them to watch what grows. You can also stick some seeds to gloves and have the children try to shake them off. Do some seeds stick better than others? NOTE: Kids can get a little crazy trying to shake the seeds off, so be sure to give each child plenty of room so they don’t accidentally hit someone during this experiment.
- Seeds that become food. Some seeds get transported to another place by being eaten. The seeds pass through an animal’s digestive tract and grow when they are excreted. What advantages might this have for a seed? How do seeds make sure they aren’t crushed and destroyed when they are eaten? Can a half-eaten seed still germinate? As an experiment, try crushing some seeds with a hammer and see if they will still grow.
- Mast year seeds. Have you noticed that some years there is a lot of acorns produced and other years there are only a few on the tree? Why might that be? How might this help a seed survive? Scientists don’t completely understand it but at irregular years, some trees have a “bumper crop” of seeds and nuts. A year of extra production is called a “mast year.” During these mast years, the abundance of seeds means there is a higher chance that some of them will not be eaten. If there were a large amount of seeds every year, the population of seed-eating animals would also increase, making the process not as effective.
Michigan State University Extension recognizes there are many opportunities for science education that occur in the natural world, including these regarding seed dispersal. Any group working with children, including families, day cares, schools or 4-H clubs, can conduct this lesson. Have fun experimenting with seeds and nuts and how they move around in the environment.