How Do Seeds Hitchhike?

Research Questions:

• How do seeds travel on animals?
• Do certain types of material facilitate seed transport more effectively?
• Must seeds fall from the plant before they can be transported?
• What types of animals in your neighborhood transport seeds?

Students will learn if certain materials facilitate seed distribution more than others. They will consider other factors such as the height of where seeds are produced, and whether the seeds must fall from the plant first.

Materials:

• Small animal skin, such as a rabbit skin from an old hat
• Piece of rayon
• Piece of denim
• Piece of wool
• 15 foot length of sturdy rope
• Sandwich bags
• Tape
• Scissors

Experimental Procedure:

1. Cut your fabrics so that you have four pieces of each material that are one foot by five inches. These are your test materials. They can be slightly smaller or larger, but they should all be the same size.
2. Form a hypothesis as to which test material is most likely to attract seeds.
3. Tie your test materials to your rope at fixed intervals at last two feet apart. Make a note as which material is at the top of the rope and what order the test materials are in. There should be four feet between the top of the rope and the first test material.
4. Survey your field and identify a 30-foot path across which you can drag your rope.
5. Take the top end of rope and drag it through the 30-foot path.
6. Remove the test materials and put each into a plastic bag. Label the bag as to the type of material and it’s position on the rope.
7. Using a new set of test materials, tie them to the rope as you did in step 3. This time, stagger them in different positions on the rope.
8. Repeat steps 4, 5 and 6. 9. Continue making new passes across the field as you did before. At the end of your experiment, you should have sixteen bags of test materials.
9. Using a hand lens and tweezer, remove any seeds that have affixed themselves to the material. Count them. Make a note as to which material attracted the most seeds.
10. Examine your seeds closely and determine how they hook themselves on to the test material.

References:

• San Francisco Botanical Garden: Plant Travelers, A Teachers Guide
• World Builders: How Seeds Travel