Why Sunflowers Follow The Sun

Why Sunflowers Follow The Sun
Sunflower behaviors follow a circadian rhythm, which helps the plants anticipate the position of the sun every morning.

Why do sunflowers follow the sun? More sunlight equals better growth, and the plants know it.

New research shows this sun-tracking is a circadian rhythm. The plants turn overnight to face east because their internal clocks anticipate sunrise.

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Biologists at the University of California, Davis demonstrated this regulation and its reliance on the sun when they moved the plants into a room with constant overhead light. Their east-west rhythm deteriorated in a few days.

And when researchers staked plants in place or turned their pots away from the sun in the mornings, they didn't grow as big as the rest.

This sun-following behavior eventually stops naturally when the sunflower matures and its priority shifts from growth to pollination.

Mature sunflowers face east constantly to catch the first rays of the sun. According to the researchers, "bees like warm flowers" — as much as five times more than cold ones.

This video includes clips from Peter Sachs / CC BY 3.0Hagop Atamian / UC Davis, the University of Wyoming / CC BY 3.0Kevin Karl / CC BY 3.0 and Nicky Creux / UC Davis and images from Chris Nicolini / UC Davis, Ben Blackman / UC Berkeley and Evan Brown / University of Virginia. Music provided courtesy of APM Music.