Inducible plant defenses against herbivory
Plants have evolved many defense mechanisms against insect herbivory in the 350 million years in which they have co-evolved. Such defenses can be broadly classified into two categories: (1) permanent, constitutive defenses, and (2) temporary, inducible defenses.
Source: Wikipedia — Inducible plant defenses against herbivory (CC BY-SA 4.0)