As you know, plants are usually anchored to the ground and can't go anywhere. But somehow, despite their relative immobility, plants are actually surprisingly good at staying alive and defending themselves.
A recent study in the journal Functional Ecology found that certain plants, when damaged, will emit a chemical that wards off insects. When neighboring plants sense the chemical, they too begin to excrete it, creating a little smelly, defensive plant pocket.
But chemicals aren't the only way plants can fight back. If you've ever reached for a rose and been stabbed by its thorns, you've stumbled onto another defensive technique. Many plants have thorns, spines, prickles, barbs, or any other name for hard, sharp, protruding body parts.
Phys.org: Plants' chemical messages keep pests moving
Scientific American: Why do flowers have scents?
NCBI: Two Volatile Organic Compounds Trigger Plant Self-Defense against a Bacterial Pathogen and a Sucking Insect in Cucumber under Open Field Conditions