The reading material points out the problem of invasive plants in America, and the lecture given by the speaker uses the example of garlic master to illustrate that how nonnative plants influence the local ecology. First, the reading material explain the reason why invasive plants be introduced into a new area. The reason includes food producing, medical uses and particle beauty of some species. In the lecture, the speaker said that the original usage of garlic mustard was because of food and medical use. But after gardening, the nonnative plant started to grow wild and invaded the new area, which caused a lot of problems. Second, the reading material points out that the invasive plants post a great threat to the native plants for some reasons, including the competition of light, space and nutrient. In the lecture, the speaker uses the example of garlic mustard to illustrate how it influences the local plants. From the plants' prospective, because garlic mustard has the similar habitat to the local plants, therefore, after it gradually get used to the new environment, garlic muster started to take over the area and shade out the native plants. Third, besides posting a great impact to native plants, invasive plants even influence the local animals. As the original habitat change, the local animals lose not only their habitat, but also the food resources. According to the example of the butterfly eggs in the lecture, because the leaves of the garlic mustard is toxic to the eggs, after it replaced the native plants, the butterfly have no choice but to lay their eggs on the leaves of garlic muster. But it turns out that those eggs cannot be hatched because of the toxic material of garlic mustard.