普通高中课程标准实验教科书 英语选修9 Unit 4 Exploring plants（在线收听） |
| 1 Before you read the text, glance quickly through it and answer these questions. 1 What's the topic of the text? 2 What three plants are featured? 3 What do the photos show you? 4 What three animal pollinators are featured? CO- EVOLUTION Some plants, like the examples given below, depend on a single species of pollinator to make its seeds. Likewise, many pollinators rely on one plant species to provide all the food for their young. The kind of evolution where two species have become totally dependent on each other is called co-evolution. The Yucca (丝兰) The yucca moth is the only animal that is the right size and shape to pollinate yucca flowers. The female moths lay their eggs in the yucca flowers. In the process, pollen sticks to the moths that then carry the pollen to another flower. The moths' caterpillars (毛虫 ) eat some of the developing yucca seeds. Although the plant loses a few seeds to the caterpillars, the moths' visits to the yucca flowers ensure pollination. The Traveller's Palm The Traveller's Palm produces large quantities of sweet nectar to attract pollinators. But the Madagascar black lemur (狐猴), a monkey-like mammal, is one of the few animals strong enough to open the flower. When it pulls the flower apart to drink the nectar, the pollen sticks to its head. Looking for more nectar, the lemur moves on to another palm, and the pollen stuck to its fur now sticks onto the new flower. So the Traveller's Palm is pollinated, and the lemur satisfies its sweet tooth. The Ophrys Orchid Ophrys is an orchid with a flower that looks, and even smells like, a certain kind of female wasp. When the male wasps come out of their pupae (蛹), they are attracted by the smell and try to mate with the flower. In doing so, they collect the pollen which is then moved to another Ophrys flower when he tries to mate with that flower. When the orchid flowers are dying, the female wasps then come out of their pupae and visit the flowers to collect a chemical, the same one to which the males were attracted earlier. The male wasps, attracted by the smell, then mate with the real females. |
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