Nyctinasty

Plants have several different types of circadian rhythm. The first is that plants orient themselves towards the sun during the day to maximize photosynthesis. Plants also undergo another circadian rhythmic nastic movement called nyctinasty. Nyctinasty is a response in higher plants to the onset of darkness. An example of nyctinasty in plants is when the leaves and petals of plants close at night. The action is brought about by darkness and is an evolutionary reaction that preserves water and sugar levels in the plant when conditions are not optimal for photosynthesis.