Why do some plants close at night?
Show answer & explanation
Answer: Nyctinasty conserves energy
Nyctinasty conserves energy ✓ — Correct! Plants like prayer plants, mimosa, and clover fold their leaves at night to conserve energy and water, reduce heat loss, and protect from cold. Special cells at leaf bases (pulvini) change pressure to move leaves—this 'nyctinasty' follows circadian rhythms. It may also reduce fungal infection or deter predators. Not true sleep, but rhythmic daily movements!
Hide from nocturnal insects — Wrong. While closing might incidentally deter some insects, the main purpose of nyctinasty is conserving water and energy, reducing heat loss, and protecting from cold temperatures at night through circadian-controlled movements.
Prevent pollen loss — Wrong. Most plants that close at night are folding leaves, not flowers. Flower closing (different mechanism) does protect pollen, but leaf nyctinasty is about conserving water, energy, and reducing heat loss through circadian rhythms.