Book 17, Question 91
Why Do Some Rainforest Seeds Spin Like Helicopters?
Some rainforest seeds have a wing that makes them spin like tiny helicopters! Tall trees, such as dipterocarps in Southeast Asia, use this trick. The spin slows the fall so the breeze can carry the seed far away.
More fun facts
- Many dipterocarp trees, like those in the rainforests of Borneo, have fruits with long wings that make them spin as they fall.
- The wings form when parts of the flower called sepals grow long.
- Scientists dropped over 650 fruits from 13 kinds of dipterocarps off a 30 meter tower in Malaysian Borneo.
- Half the fruits landed less than 4 meters away, and 90 percent landed within 10.5 meters.
- Fruits with more wing area for their weight traveled farther, especially in strong wind.
- About 30 percent of dipterocarps have no wings or weak ones, and their fruits fall right under the parent tree.
- Other studies found the farthest spinning fruits traveled 20 to 80 meters.
Sources: National Institutes of Health
Questions kids ask
Do these trees all drop fruit at the same time?
Sometimes. In 2010 there was a community-wide mast fruiting event, when many dipterocarp trees fruited together.