Sunflower Field, Photo : Taufique Hassan
Scientists from the University of California and University of Virginia have recently published a paper answering this age-old question.
According to the paper:
- Young sunflowers follow the sun to provide a growth boost.
- Even when exposed to artificial light, the sunflowers would track that movement in a consistent cycle.
- Adult sunflowers do not follow the sun. They just face east. Being warm in the morning when insects are more active offers an advantage for pollination.
The movement of the sunflower is due to the uneven growth of the stem. One side of the stem elongates during the day and the other side at night. This growth is driven by genes that respond to light and plant’s circadian rhythm (a biological process that displays an oscillation of about 24 hours). So, the internal clock of the sunflower plants and capability of detecting light work together to turn on the genes related to growth at just the right time allow the stems to bend with the arc of the sun.
Here is a video demonstration: