Earlier quoted context omitted.
Panic is not the same as fear. Panic (insert here mythological reference to god Pan) is a kind of fear that causes uncontrolled, irrational and often counterproductive behaviour. Is that the case?
'uncontrolled and irrational' is only a bad thing in the context of human rationality and self control. plants obviously do not have such a thing--all their actions are primal and unmoderated. So panic for a plant would probably mean something like an immediate response to adverse stimuli, with an immediate and short-term goal of self-preservation.
"panic" means to react in a counterproductive way because fear overwhelms.
It's different from a mere adrenal response that has short term gain at long term risk.
Adrenaline makes you jump higher. Panic makes you jump off a cliff.