Plant defense refers to the mechanisms and strategies that plants use to protect themselves from herbivores, pathogens, and other threats in their environment. This can include physical defenses such as thorns, spines, and tough outer layers, as well as chemical defenses such as toxins and repellent compounds. Plants may also have inducible defenses that are triggered in response to specific threats, such as releasing volatile compounds to attract predators of herbivores. Understanding plant defense mechanisms is important for agriculture, as it can help in developing strategies to protect crops from pests and diseases without relying on harmful chemical pesticides.