TOEFL Speaking Task 3 Practice 002Science

Narrator:Now listen to part of a lecture in a botany class.

Professor:Ok, so here's one example of this. Researchers have been studying a particular plant that lives in the desert. It's called a creosote plant. Now, when you look at creosote plants, you notice something unusual about them right away. You see that they're spaced far away from other plants. And as it turns out, there's a reason for that. Like other plants, a creosote plant has a root system underneath the ground that provides the plant with access to the water the plant needs to survive. And the creosote plant has a special way of protecting the space around its roots. More specifically, of protecting the water in the space around its roots. What it does is whenever the roots of other plants start growing too close, the roots of the creosote release a chemical. When the roots of the other plants come into contact with this chemical, they stop growing toward the creosote roots and start growing in some other direction away from the creosote plant. So in a way, the creosote roots with this chemical they release are telling the roots of the other plants, "This is my space and my water." And the other plants get the message and move away. So this way, the roots of the creosote plant always have plenty of space around them. And in a dry desert climate, that's a big advantage.