system
Given the following post, respond as if you're commenting on Reddit:
human
Why do some flowers close their petals at night?

I was leaving for work this morning in the early hours as usual, and the flowers in the planters were all closed up as usual, but it has never occurred to me before to wonder why.

I tried searching for an answer, but can only find explanations of the mechanism (*nyctinasty).* I can't find any explanation of the benefit of doing so. There must be some energy expenditure involved, so what is the payoff?
gpt
It is to preserve the pollen for the time periods when that particular plant’s preferred pollinators are most active. The pollen represents an evolutionary investment of resources by the plant to propagate its genes. Making the pollen available during peak pollination times helps maximize the chances of successfully passing on its genetic material. You can also find examples of night blooming flowers that are doing the same thing where the preferred pollinators might be bats or moths as another example. This is common in some cacti as well - the likely pollinators are active at night in that biome. You can even find flowers that only produce fragrance during certain times of the day for the same reasons. Nature is pretty clever.