About us: We own the Wild Birds Unlimited nature shop in East Lansing, Michigan,
a store that provides a wide variety of supplies to help you enjoy the birdwatching hobby.

This blog was created to answer frequently asked questions & to share nature stories and photographs.
To contribute, email me at bloubird@gmail.com.

Monday, August 15, 2016

Why sunflower heads follow the sun

Mature sunflower heads face east typically and do not move. The leaves and buds of young sunflowers however exhibit heliotropism (sun turning). Before the fruit of the sunflowers is produced sunflower heads track the sun across the sky, turning their flowers from east to west as the day progresses, and then return to the east overnight. New research has finally been able to figure out exactly how this happens.

To see if the plants had their own biological clocks that were reset daily by the sun, similar to our own, or were simply moving according to a pre-determined schedule, the team performed a series of experiments.

First they staked the plants so they couldn't move, then they brought the flowers into an indoor lab with a fixed artificial light, and finally the researchers created a different 'daylight' cycles. 

Throughout their experiments, the team showed that flowers tethered away from the sun had leaves that were 10 percent smaller on average. One side of the stem grows faster than the other, depending on the time of day, causing the plant to swing its head. And they also showed that eastward-oriented flowers are warmer than westward-oriented flowers, and this warmth attracts pollinators, suggesting there's an evolutionary benefit to the plants chasing the sun.

The research has been published in the journal Science.

Related Articles:
Sunflowers Up-close: The Strange Journey of an American Plant http://bit.ly/uFlz65
Which seeds are preferred by wild birds? http://bit.ly/zchLgB
How long does bird seed stay fresh? http://bit.ly/rTLSqJ
Seed Storage Cans and WBU Seed Scoops http://bit.ly/uBaSwO

Sunflower seeds benefits http://sunflower-seeds-benefits.html

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