托福口语 Task 4

Today, I want to talk about a fascinating survival strategy used by some plants called 'allelopathy.' Allelopathy is when a plant releases chemicals into the soil that inhibit the growth of nearby competing plants. This gives the plant a competitive advantage for water, nutrients, and sunlight. Let me give you two examples. First, consider the black walnut tree. It produces a chemical called juglone, which is released through its roots and leaves. When juglone enters the soil, it can stunt the growth or even kill many other plants, like tomato plants or azaleas, that try to grow nearby. This allows the walnut tree to have more space and resources. Second, think about the sunflower. Sunflowers also exhibit allelopathy. Their roots secrete chemicals that prevent the seeds of certain grasses from germinating. So, in a field where sunflowers have grown, other plants often fail to sprout. This ensures the sunflowers have less competition from weeds. So, as you can see, allelopathy is a clever way for plants to secure their own survival.