Why do old sunflowers face east?

Thanks to the early sun’s soft warmth, sunflowers facing east are happier, healthier, and more productive than those facing west.

This conclusion was reached after a new investigation was conducted to determine why sunflowers age by turning east and more flexible young flowers alter orientation towards the moving sun.

More bees are attracted to the rising sun by the heat and light, which stimulates better growth, faster pollen production, more seeds, and higher reproduction in the morning. Young sunflowers (Helianthus annuus) have a unique habit as they grow: the flower head moves in time with the sun’s journey across the sky.

Harmer and her colleagues discovered in a 2016 study that this tracking improves both plant and flower growth and pollinator attraction. The stem of the sunflower grows stiff as it ages, restricting movement greatly. When this occurs, the sunflower will no longer face east.

This was a mystery to academics until recently, so a team led by a biologist from the University of California devised an experiment to find out.

Making it impossible for the sunflower to turn east is one technique to figure out why this is happening. The researchers rotated the flower around, obtaining measurements, and compared the sunflowers facing west and east in this case.

The key discovery was that in the morning, flowers facing east attracted much more bees. The bees did not seem to be as active the rest of the time. Early in the morning, the east-facing blooms began to shed pollen, coinciding with peak pollinator visits.

The following result was as impressive. The bloom facing east generated more seeds and was heavier than the flower facing west. These sunflowers’ pollen was proven to be more effective in creating offspring.