Morphological defense mechanisms:
1. Opuntia and cactus leaves undergo morphological changes, transforming into sharp spines or thorns, serving as a defense mechanism to deter herbivores from feeding on them.
2. Certain plants exhibit spiny leaf margins, creating sharp edges that pose challenges for herbivores attempting to consume them.
3. Acacia plants employ a defense strategy by incorporating sharp thorns alongside their leaves, effectively discouraging herbivores from feeding on them.
Chemical defense mechanisms:
1. Plants like Calotropis weeds produce lethal cardiac glycosides throughout their entire structure as a defense mechanism against herbivores, causing potentially fatal cardiac issues if consumed.
2. Caffeine, nicotine, opium, and quinine are examples of chemical substances in certain plants that serve as a response and defense mechanism against herbivory. Similarly, all parts of Calotropis weeds contain deadly cardiac glycosides, posing a lethal threat to herbivores if ingested.