The Great Sunflower Project

Finally our sunflowers bloomed here in foggy Northern California. Tight green buds guarded by row after row of pennant-shaped leaves gave way to full-flowered glory. Some flowers have already faded away and are now growing fat with seeds in the summer sun. Sunflowers didn’t come by their name by accident. They literally follow the sun with their broad round heads. Their buds and leaves, in their natural position, are oriented toward the East so they can catch the first rays of dawn. As the sun arcs overhead, specialized cells expand and contract turning the flower head to track the sun’s rays. By the end of the day, the flower heads are positioned toward the West and the last warm rays. This feature is known as “Phototropism” – literally turning to the light. Indole acetic acid (IAA) is a plant hormone that stimulates cell growth wherever it is in the plant. It moves easily around a plant and is very sensitive to light. At night, it is distributed throughout a plant. During the day, it moves to wherever there is shade. This causes the stem cells to expand on whichever part of the plant is in the sun. Even sunflower seedlings respond to light. Here is a wonderful video of sunflower seedlings dancing in response to white light (http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/phot...). In many arctic and alpine plants, insects are attracted to the warm flowers that follow the sun – increasing the plants pollinator visits. It would be interesting to see if the temperature of our sunflowers influence the bees per hour.

While some high-end solar panels use motors and electronic controls to orient panels to efficiently capture the most sunlight, these beautiful head-turners do it naturally, as part of their daily routine. Once the stem becomes woody, the plants no longer turn with the sun and come to a dead stop. Others that are still growing and blooming, reset during the night so that they are once again poised to trace the sun’s path through another day.

Thanks to all of you who have sent in head-turning pictures of your sunflowers. We’re working on making the web site more “photo – friendly”, but in the meanwhile, I’d like to share one of our photos with you. This one is from member Larry S. and features a Texas field of sunflowers with a fat Apis mellifera enjoying the scene.

So, a couple of tips: It’s okay to deadhead some of your sunflowers which have finished blooming to encourage the rest of the plant to keep at it. That allows time for another observation or two this season. And, if all that head-turning is making your sunflower unsteady on its feet, now would be the time to add a supporting stake or two to keep it upright and blooming freely.

Our data map, observations and just plain wonder at how nature works is the reason we decide to take action to preserve and enhance habitat for pollinators. Keep up the great work.

We still have more time to make observations this year, so if you can, please do so and send in your sample data. That will make this y ear’s map so much more precise and relevant.

Best,

Freddy B