>>11065895
You're absolutely right, we're talking leafs, bark and branches though.
There is a type of african tree, that'll release an airborne trigger, when Giraffes starting munching their leafs. The trigger is received by other trees of the same species and they start producing acidy tasting fluids and pumping them into their leafs. Over time this has resulted in giraffes eating the leafs of a single tree and then always moving against the direction of the wind, to the next one.
Another example is a south american tree, that'll warn it's fellow trees about bark eating insects. The other trees will then produce a bad tasting chemical and store in in their bark, for extend periods of time. Afaik, this is done via the root network though, not an airborne trigger.
>>11065907
Never heard about that, I thought tobacco survived mostly, because nicotin is already an insectizide, afair. But the technique sounds reasonably realistic, to exist.