It's summertime, and the fields of Yolo County, Calif., are filled with rows of sunflowers, dutifully facing the rising sun.
At the nearby University of California, Davis, plant biologists have now discovered how sunflowers use their internal circadian "clocks," acting on growth hormones, to follow the sun during the day as they grow.
"It's the first example of a plant's clock modulating growth in a natural environment, and having real repercussions for the plant," said Stacey Harmer, a plant biologist at UC Davis and senior author of a paper reporting the discovery published this week in the journal Science.