How Plants Tell Time

Plants can move without muscles or nervous systems through processes like nyctinasty and heliotropism. Nyctinasty involves leaf movements in response to non-directional stimuli, influenced by temperature and chemical reactions. Phytochrome, a light-absorbing molecule, plays a key role in these movements by cycling between forms Pr and Pfr. Turgor pressure in pulvini helps flex leaves. Heliotropism, a directional movement, allows plants to track the sun, with sunflowers using auxin to grow towards light. These processes show plants' sophisticated responses to their environment.

What is heliotropism and how does it benefit plants?

Describe how young sunflowers track the sun throughout the day.

In what ways do plants respond to their environments without having brains or nervous systems?