Although plants have no immune systems, they do have many chemical and physical methods of defence against pathogens and attacks by insects - VCE - SSCE Biology - Question 2 - 2017 - Paper 1

One example of a physical method of defence in plants is the formation of a wavy cuticle on the leaves. This structure serves as a barrier to pathogens by creating a physical obstacle that prevents them from entering the plant's tissues. Additionally, a thick bark formation can also prevent herbivores from accessing internal plant structures, thereby reducing the chances of damage from insect attacks and disease.