Gone with the Wind: Plant Seed Dispersal
Models of four types of seeds
Have you ever looked outside on a windy day and seen "helicopter" seeds spinning through the air? Or picked up a dandelion and blown on it, sending the tiny, fluffy seeds flying all over the place? Wind is very important for dispersing seeds to help plants reproduce. In this project you will design some of your own "seeds" and see which ones work best when they are blown across the room by a fan.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Dispersal of seeds is very important for the survival of a plant species. If plants grow too closely together, they have to compete for light, water, and nutrients from the soil. Seed dispersal allows plants to spread out from a wide area and avoid competing with each other for resources.
Seeds are dispersed in several different ways. In some plants, seeds are housed within a fruit (like apples or oranges). These fruits, including the seeds, are eaten by animals who then disperse the seeds. Some fruits can be carried by water, like a coconut. Some fruits have little hooks that can stick on to an animal's furry coat (you may have gotten them stuck on your clothing if you ever went hiking in the woods).
Other seeds are dispersed by the wind – like the "winged" seeds from a maple tree that spin and helicopter through the air as they fall, or the light, feathery seeds from a dandelion. The longer a seed stays in the air, the farther it can be blown by the wind, helping the plant species spread out its offspring. In this project, you will make your own artificial "seeds" from craft materials- can you design seeds that will stay in the air for a long time?
Extra: have a friend use a stopwatch to time how long it takes the seeds to hit the ground. This might be easier if you drop the seeds from a higher location (have a tall adult drop them, stand on a chair, or drop them from the top of the steps).
Extra: use a tape measure to record how far the seeds travel horizontally from where you drop them to where they hit the ground. Which seeds go the farthest?
Extra: how do your results change if you change the speed of the fan?
Observations and Results
You should find that adding light materials to the "seed" can make it fall slower and blow farther, however the shape of the materials is very important. For example, a paper clip attached to a crumpled-up piece of paper will still fall very fast. However, a piece of paper with a "wing" design (like a maple seed) or a bunch of individual streamers (like a dandelion seed) will fall slower and be blown farther by the fan. Exactly how far the seeds blow will depend on the strength of your fan, but you should definitely see a difference in the horizontal distance traveled between a "plain" seed and one with a dispersal mechanism. When you take your best designs and try to improve on them, you mimic the process of evolution – since the "best" seed designs in nature are the most likely to reproduce!
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Ben Finio, PhD, Science Buddies
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