Plant behavior

With all the excitement of the solar eclipse this past week, I wondered if any gardeners happened to check out their plants during the eclipse. I know I didn’t. My husband and I were sitting on the edge of a large boulder off of Trail Ridge Road hoping for a glimpse of something awe-inspiring. Instead of being able to concentrate on the alpine flowers and the eclipse, I ended up being mostly concerned about my husband maneuvering around the top of this large rock with his eclipse glasses on. It’s impossible to see anything other than the sun with those glasses and it was a long ways down!

There isn’t much research on how plants or animals react during a solar eclipse, but it did remind me of some fascinating ways plants regularly interact with their environment. Most folks have heard of heliotropism. It’s when plants orient their leaves or flowers to track the sun throughout the day. Are you thinking about sunflowers now?

According to the University of Indiana, the immature flower buds of cultivated sunflowers (Helianthus annus) do track the sun, but the mature flowers do not. The mature plants will, however, reorient their leaves to the east overnight. Here’s a 30 second video the university produced. It’s quite nifty to see the plant redirect itself overnight: http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/solartrack/solartrack.html

If you want to see solar tracking in person, spend some time with the snow buttercup (Ranunculus adoneus) located in our alpine and subalpine regions. Researchers think that by following the sun, the inside of the flower warms itself up making it an attractive landing pad for pollinators.

Can plants think? Well, yes and no. They definitely take in information from their environment and then respond, but they obviously don’t have brains. Some scientists believe plants have a type of intelligence, because they can sense, learn and remember.

One example of a plant sensing its environment is thigmotropism. How does a plant, such as the sweet pea, curl its tendrils in order to grow up a lattice? The plant “feels” a solid object, then exhibits a coiling response. Kenyon College states that “plants are actually more sensitive to touch than human beings” and some plants have a sense of touch nearly 10 times that of a human.

What about those of you who plant your tomatoes sideways in a trench? The plant will send the root down and the shoot up, right? This is known as gravitropism. The plant “knows” which way is up and which way is down.

Stefano Mancuso is one of the founders of a fairly new field of study called plant neurobiology. His organization studies plant intelligence, behavior, signaling and communication. They believe “plants are as sophisticated in behavior as animals”. For more information: http://www.linv.org/. You can also search YouTube for some of his TED talks.

Here’s another resource for you if the subject matter interests you. It absolutely intrigues me! Three minute video with Michael Pollan talking about how time-lapse photography can help us to better understand plant life. https://youtu.be/MPql1VHbYl4.

Kelley Rawlsky has an M.S. in horticulture and is the director of Bringing People and Plants Together, an organization dedicated to bringing horticulture education and therapy to the community. For more information: PeopleAndPlantsTogether@gmail.com or follow us on Facebook.

Article originally published in Broomfield Enterprise - Aug 27, 2017