OverviewStudents will be able to explain various methods of seed dispersal and how animals and natural processes play a role in helping plants reproduce.
Students will be able to explain various methods of seed dispersal and how animals and natural processes play a role in helping plants reproduce.
Plants and animals need each other to exist. Animals depend on plants for food and shelter, and plants depend upon animals for obtaining nutrients from their waste products and help with seed dispersal. Many seeds are carried and dispersed by animals, catching a ride on fur or perhaps eaten as a seed, fruit, or berry. Often, in island ecosystems, birds are responsible for seed dispersal and carry the first plant life into those isolated places.
Plants also take advantage of natural processes to assist in seed dispersal. Wind and water are fundamental methods of seed transportation. Some plants develop elaborate structural designs in order to keep their seeds afloat for as long as possible.
Some plants, such as needle-and-thread grass (Stipa comata), have the ability to plant themselves. After a seed is blown free of its sheath, it falls to the ground. As the temperature and humidity changes, the long awn (thread part of the seed) will twist and untwist. The twisting motion will often bore it into the ground.
Explore Great Sand Dunes' web page on plants for more about the wide variety of plants in the park and preserve.
Socks (old fuzzy or cotton socks work well), small container or plastic baggies for seeds, Great Sand Dunes Plant Handbook (optional, PDF)
Best when timed for midsummer to late fall.
In advance of your lesson, divide the class into groups of three. Each student will be assigned a specific type of seed dispersal to look for: seeds that catch a ride on an animal's fur (these students should wear fuzzy socks or corduroy pants on the day of the trip), seeds that are blown by the wind, and seeds with other unique adaptations (such as needle-and-thread grass).
On the day of your lesson, choose an area in the grassland or where the grassland meets the forest. Define boundaries and let each group search for about ten minutes. Have students in each group show one another what they found. It is permissible for students to collect seeds for this activity, but they shouldn't break any part of the rest of the plant.
Have each group classify their seeds according to dispersal method. One student should record their findings in a group notebook. If possible, they should try to find out what kind of plant their seeds come from.
Each group will then take their most special seeds and show them to the entire class. They should explain where the seed was found, what plant they think it is from, and what they think the adaptation for dispersal is. Seeds should be released to the wind at the end of this activity.
Discuss seed dispersal methods with your students. How many can they think of? Is it possible that plants and animals have coevolved? How do plants develop such fantastic structures for their seeds?