Name important defence mechanisms in plants against herbivory.

(N/A) Plants have evolved various morphological and chemical mechanisms to protect themselves against herbivory.
Morphological defence mechanisms:
$1$. $Opuntia$ (cactus) leaves are modified into sharp spines (thorns) to deter herbivores.
$2$. $Acacia$ plants possess sharp thorns to discourage herbivores from feeding.
$3$. Some plants have spiny leaf margins or sharp edges to prevent herbivory.
Chemical defence mechanisms:
$1$. $Calotropis$ weeds produce toxic cardiac glycosides,which are fatal if ingested by herbivores.
$2$. Plants produce various chemical substances like nicotine,caffeine,quinine,and opium as a part of their self-defence strategy against grazers and browsers.