State two important defense mechanisms in plants against herbivory, with an example each.

Explanation

Plants have evolved an astonishing variety of morphological and chemical defenses against herbivores.
Thorns (Acacia, Cactus) are the most common morphological means of defence.
Many plants produce and store chemicals that make the herbivore sick when they are eaten, inhibit feeding or digestion, disrupt its reproduction or even kill it.
The weed Calotropis growing in abandoned fields. The plant produces highly poisonous cardiac glycosides and that is why you never see any cattle or goats browsing on this plant.
A wide variety of chemical substances that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.,) are produced by them actually as defenses against grazers and browsers.