Sunflowers Facing The Moon?

Nyctinasty is a phenomenon in which sunflowers open their petals to seek out the moon’s pale light when the sun sets and darkness falls. This process, known as heliotropism, is triggered by changes in the light and the movement of the sun. Sunflowers move during the day, pivoting to face the sun as it moves across the sky and rotating 180 degrees at night to greet the morning sun.

New research has revealed that the plant’s internal clock and ability to detect light work together to allow the flower to face east as the sun rises and bend to the west. Younger flower heads exhibit this characteristic because they have green “bracts” that look like a mane. Sunflowers not only pivot to face the sun during the day but also rotate 180 degrees during the night to greet the morning sun.

Sunflowers use their internal circadian clock acting on growth hormones to face east at dawn and follow the sun during the day. Mature sunflowers face east, while younger blooms are more flexible, changing their position to face the sun as it moves across the sky. At night, in its absence, the sunflowers face east again, anticipating the sun’s return.

Researchers say that the young plant’s sun-tracking (also called heliotropism) can be explained by circadian rhythms. Sunflowers in full bloom are not heliotropic, so they do not follow the sun. Instead, they face east all day, so in the afternoon, they are backlit by the sun.

Sunflowers use their internal circadian clock acting on growth hormones to face east at dawn and follow the sun during the day. Heliotropism is a motion in response to the direction of the sun, and it is a vital part for photosynthesis.