The author mentioned some suggestion like having ONE plant in a field that was extra-vulnerable to aphids. That way, they would attack the vulnerable plant first, and trigger all the plants in the field to unleash their protective chemicals.
But if there were no aphids at all, the plants would not use up the energy and nutrients consumed in the anti-aphid-defense. They only go to war when they need to!
I have never been able to go back and find again something that I read somewhere. It claimed that some species actually do BETTER as seedling if they are crowded up against other seedlings of their own species.
They are actually encouraged by close neighbors, at least as seedlings, if the neighbors are the same species. Or so he or she claimed.
Cooperative crowding? There was a name for it, but I forget what that was.
I could believe that Lobelia work that way: I've never seen a single Lobelia, only masses. Maybe daisies?
