Do sunflower heads really follow the sun?
It's sunflower season! Have you been looking at them as you hike in Lambert Park? Are the flower heads facing the sun as it moves across the sky from east to west? In general, it appears to be so, but there are always a few independent sunflowers that face in the opposite or sideways directions. Why is that?
It turns out that only the immature flowers follow the sun. The stems have hormones called auxins that migrate from the one side of the stem to the other. The auxins seek the shade, and as they migrate to the west of the plant in the morning, the stem on the west side hardens and the flower head bends towards the east. Warm plants attract insects that pollinate, so it is in the plant's best interest to follow the sun.
As the plant matures and develops heavy seeds it ends up not following the sun and mainly facing east. Keep an eye on them this fall to see if this appears to be true. For more information, go to:
https://www.scienceabc.com/nature/sunflowers-always-face-follow-sun.html
It turns out that only the immature flowers follow the sun. The stems have hormones called auxins that migrate from the one side of the stem to the other. The auxins seek the shade, and as they migrate to the west of the plant in the morning, the stem on the west side hardens and the flower head bends towards the east. Warm plants attract insects that pollinate, so it is in the plant's best interest to follow the sun.
As the plant matures and develops heavy seeds it ends up not following the sun and mainly facing east. Keep an eye on them this fall to see if this appears to be true. For more information, go to:
https://www.scienceabc.com/nature/sunflowers-always-face-follow-sun.html