You are actually thinking in plant-animal interactions.

Maybe their goal is just to photosynthetize and grow and the bitter flavors and other products and interactions are not that important (for them).

I don't know. Maybe they're high tech time travelling solar panels and radiator systems sent back to prevent the early drying of the planet.

Can you think of plants outside of the traditional evolutionary paradigm, just for a while? That is the challenge of this idea.