For plants, herbivores are the predators. Nearly 25 per cent of all insects are known to be phytophagous (feeding on plant sap and other parts of plants). Plants cannot escape from predator like animals. So, plants have developed a variety of morphological and chemical defence to escape herbivores animals. The various methods adapted by plants are enlisted below:

1. Morphological defence mechanism:

A. Sharp thorns present in plants such as Acacia and Cactus is the most common morphological means of defence.

B. In some plants, the margins of their leaves are spiny or have sharp edges that prevent herbivores from feeding on them.

2. Chemical defence mechanism:

A. Chemical substances such as nicotine, caffeine, quinine, and opium are produced in plants as a part of self-defence.

B. Calotropins weeds contain toxic cardiac glycosides, which can be fatal if ingested by herbivores.