You might have seen time-lapsed videos showing how sunflowers move their yellow-petaled heads during the day in coordination with the sun and thought, perhaps, that it was the sun driving this movement.

While this might be true in part, some researchers recently found that the sun isn’t the only factor playing into this movement.

Biologists Hagop Atamian and Stacey Harmer with the University of California, Davis, grew sunflowers outside at first and then transferred them inside where there was only an overhead light in a fixed position. According to Nature, the sunflowers still moved their heads from east to west.

Photo credit: Shutterstock

Photo credit: Shutterstock

“It brings into question whether there’s some sort of memory that’s found within the plant that allows this regulation,” Mark Belmonte, a plant biologist at the University of Mannitoba, who was not involved with the study, told Nature. “This could be a very fine-tuned process.”

Bending in the sunflowers was also caused by one side of the stem growing faster than the other, the UC Davis biologists said, presenting their findings at the American Society of Plant Biologists’ meeting this week.

“Somehow the same clock in the same organ is having opposite effects on opposite sides of the stem,” Atamian said. “It’s a big open question.”

Watch Atmain’s video of the sunflower’s movement:

Front page image via Shutterstock.