Plant Barriers and Chemical Defenses

Plants use barriers, chemicals, and proteins to defend against herbivores and pathogens. Because they are rich in nutrients, plants attract animals that eat them and infectious agents that try to invade them. Even without a true immune system, plants have built both constant defenses and defenses that turn on after attack.

Plants cannot flee from attackers, such as plant-eating animals or pathogens. Nevertheless, the world around us is green. What defense mechanisms did plants evolve to combat these attacks?

The tough layers of the epidermis and other structural defenses, such as hairs and thorns, deter plant-eating animals—also called herbivores.

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