Heliotropism

Heliotropism, a form of tropism, is the diurnal or seasonal motion of plant parts (flowers or leaves) in response to the direction of the Sun.

In the 19th century, however, botanists discovered that growth processes in the plant were involved, and conducted increasingly in-depth experiments.

The French scientist Jean-Jacques d'Ortous de Mairan was one of the first to study heliotropism when he experimented with the Mimosa pudica plant.

Daisies or Bellis perennis close their petals at night but open in the morning light and then follow the sun as the day progresses.

The motor cells are specialized in pumping potassium ions into nearby tissues, changing their turgor pressure.

For plant organs that lack pulvini, heliotropism can occur through irreversible cell expansion producing particular growth patterns.

If solar tracking is exact, the sun’s rays would always enter the corolla tube and warm the gynoecium, a process which could be dangerous in a tropical climate.