(上海)牛津版九年级上册
In deserts, where there is not much rainfall, trees need to hold water. The baobab tree saves water in its trunk. The trunk gets smaller as it uses up the water. The northern areas of the world, like North America, Russia and Scandinavia, are covered with tall pine trees. These trees can live well though the sunlight is not very strong. Some mountain trees are very small and grow very close to the ground. This protects them from the strong winds that blow on the mountains.