托福口语 Task 4

Today we're going to talk about a fascinating survival strategy used by some plants: allelopathy. Allelopathy is a process where a plant releases chemicals into the soil to inhibit the growth of competing plants nearby. This gives the plant a competitive advantage for resources like water, nutrients, and sunlight. Let me give you two classic examples. First, the black walnut tree. It produces a chemical called juglone, which it releases through its roots and leaves. When juglone seeps into the soil, it can stunt the growth or even kill many other plants, such as tomato plants or potatoes, that try to grow within its root zone. Second, consider the sagebrush, a common shrub in dry areas. Sagebrush releases volatile chemicals, especially during hot weather, which can be carried by the wind and absorbed by nearby plants or soil. This chemical, called camphor, reduces seed germination and root growth of grasses and other seedlings. As a result, sagebrush reduces competition for scarce water in arid environments. So, allelopathy is a chemical warfare that helps certain plants secure their territory.