When it comes to plant rhythms, Stacey Harmer, a professor of plant biology at the University of California, Davis, is hip to the groove. Her research, which appeared in the August 5, 2016 journal of Science, describes how sunflowers track the sun, beginning each morning with their heads facing east, slowly swinging west throughout the day and then resetting eastward at night.

It’s summertime, and the fields of Yolo County are filled with ranks of sunflowers, dutifully watching the rising sun. At the nearby University of California, Davis, plant biologists have now discovered how sunflowers use their internal circadian clock, acting on growth hormones, to follow the sun during the day as they grow.