Sunflower head in summertime, Provence, France.

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Sunflowers in the bud stage exhibit heliotropism. At sunrise, the faces of most sunflowers are turned towards the East. Over the course of the day, they move to track the sun from East to West, while at night they return to an Eastward orientation. This motion is performed by motor cells in hte pulvinus, a flexible segment of the stem just below the bud. As the bud stage ends, the stem stiffens and the blooming stage is reached.

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Size: 3699px × 4770px
Location: Fields of sunflowers near Riaz, Provence.
Photo credit: © David Cantrille / Alamy / Afripics
License: Licensed
Model Released: No

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