Airdate: Jul 16, 2004
Scientist: Christopher Birkinshaw
Seed Dispersal - 101
What are the different strategies plants use to spread their seeds around?
ambience: Dawn chorus, CA Sierra
Most plants reproduce with seeds and there are nearly as many different shapes, sizes and types of seeds as there are species of plants. But just as important as the design of the seed is the way it is dispersed -- and there are numerous strategies. I'm Jim Metzner, and this is the Pulse of the Planet.
Christopher Birkinshaw is with the Missouri Botanic Garden.
"In the temperate forests of, for example North America and Europe, seed dispersal by wind is very frequent. For example, your sycamores, your ashes, are all dispersed by wind. In these temperate countries, too, there is quite a lot of bird dispersal. Other methods of seed dispersal might be by water, or even by sea. For example, coconuts are a plant species whose seeds are spread by the sea."
"You’ve got seed dispersal by bats and by monkeys, and also there’s some examples of seed dispersal by reptiles - like tortoises - and also fish. So nearly every group of animal potentially can be a seed disperser. And don’t forget that some seed dispersal is not done by the animal swallowing the seed and passing it later, but is actually done by the seed clinging onto the fur of the animal."
"Normally, you can get information about what sort of seed dispersal a plant has by looking at the characteristics of its seed or fruit. So, a seed which is dispersed by an animal eating it, will normally have to have some sort of reward for the animal. Animals disperse seeds not because they're good-natured and want to help out the plants, but because they're looking for food. So, normally, a plant which is spread by animals will have some sort of fleshy reward."
We'll hear more about seed dispersal in future programs.
Pulse of the Planet is made possible by the National Science Foundation. I'm Jim Metzner.