Most people think of plants as very passive organisms.
They grow almost unperceptively, and only once a year do they flower or produce edible products. However, plants are very active in ways that are not so obvious to the casual observer. For example, plants change the chemistry of the soil, and influence the types of microorganisms that grow there. They actively compete with other plants for space. Some will poison their neighbor's offspring to maintain a competitive advantage, while others change the environment in ways that benefit other species.