One, you're adding intent to a process that has no intent.
It's not reflected- it's just not used (and thus absorbed). If the plant has more energy that it needs already to produce offspring... what pressures exist to produce more?
> an extinction level event that filtered sunlight for a long time, removing green
The lack of green sunlight would not necessarily result in a mutation that reflects green. There is no evolutionary pressure for reflecting/not using something that doesn't exist. In fact, it would be adding intent to a process that has no intent.
It's not reflected- it's just not used (and thus absorbed). If the plant has more energy that it needs already to produce offspring... what pressures exist to produce more?