Hank likes to plant seeds. This spring we prepared the soil and put a lot of sunflower seeds in the garden. The whole family and a few of the neighbors have enjoyed watching them grow. The one pictured is well over six feet tall and still moving skyward. This week they started to bloom and we have watched them gracefully unfold. As I was telling Hank everything I thought I knew about the species, I realized they were not tracking the sun. This is not a phenomenon created by the upcoming eclipse. Although the Indiana education plants-in-motion website will tell you that immature flower buds of the sunflower do exhibit solar tracking and on sunny days the buds will track the sun across the sky. As the flower bud matures and blossoms, the stem stiffens and the flower becomes fixed facing the eastward direction. All of Hank’s sunflowers are now faced east.
Well almost all of the sunflowers are facing East. We have one wild sunflower plant that has flowers facing many directions – they do not follow the sun either. To confuse the issue, the leaves of the wild sunflower do exhibit some solar tracking. You can take heart, the flowers of some plant species track the sun across the sky. The alpine plant called snow buttercup does track the sun – probably less for heliotropism or photosynthesis but for warmth. The heat is thought to help pollination since the insect pollinators will warm and be able to fly better in the cold air to deliver pollen to other plants.
To add to the complexity of plants in motion, it is reported that some have Circadian movements-evidence of an innate internal clock that may trigger the tracking movements. “Circadian rhythms are physical, mental and behavioral changes that follow roughly a 24 hour cycle, responding primarily to light and darkness in an organism’s environment.” The study of the rhythms is called chronobiology. I believe jet lag is attributed to this state of rhythmic confusion.
Expect some unusual behavior this week as humans by the millions track the sun into the totality zone. A Dutch proverb suggests, “if all fools could fly the sun would be eclipsed forever.” You would not need eye protection for that event. Drive safely and wear the certified glasses if you will be in the zone.
Enjoy the week end. Mike