----Populations and Ecosystems
----Behavior of Organisms
----Diversity and Adaptations of Organisms
----Natural and human-induced hazards
Students learn the science behind plants’ nonverbal forms of communication. (One species known to communicate is the willow tree. See the trunk of a Scottish willow tree above.)
Plants, ecology, ecosystem, survival, nervous system, nature, environment, communication, science, biology
Humans’ senses of touch, taste, smell, sight and hearing help them interpret the world around them. We know that other creatures—whether other mammals, fish, birds or even plants—take in their existence differently.
It’s clear that living things with eyes, ears and mouths can communicate, but what if these organs aren’t present? Plants are often seen as sedentary organisms with little going on except for feeding and growing, yet we are learning that plants are doing far more. While not taken seriously at first, the science of plant communication continues to develop.
As a class, read the writeup on plant communication below. Afterwards, look at the image below. Have students explain what it represents, using examples from scientific findings on plant communication.
An ecologist at the University of California, Richard Karban is in the northern Sierra Nevada studying plants’ communication, in the hopes of deciphering their “language.” A story, reprinted in Wired with permission from Quanta Magazine, follows Karban’s journey.
The article discusses two studies, published in 1983, that demonstrated how willow trees, poplars and sugar maples send warning signals to each other regarding insect attacks and infestations. In response, trees that had yet to be attacked started sending out their own natural bug repellent in preparation for the approaching pests. This indicated that the trees were actually communicating in a very sophisticated way.
Scientists studied the trees in a variety of settings and were able to replicate the findings (i.e., obtain them multiple times).
University of Lausanne scientist Ted Farmer is also central to the Wired article. He discovered that plants actually send messages via electrical pulses through a voltage system, not unlike the nervous system of an animal. The article notes, however, that this doesn’t equate to plants having neurons or brains.
Farmer and his team hooked Arabidopsis thaliana leaves and stalks to tiny microelectrodes. Then they let the plants be consumed by Egyptian cotton leaf worms. Voltage changes radiated from the damaged plant tissue to the stem, moving out into the rest of the system. The result was a defense compound (known as jasmonic acid) building up all over the plant.
The plant genes that transmit the electrical signals make channels in membranes just within the plant’s cell walls. These channels regulate the passage of the charged ions and are similar to the ion-regulating receptors present in animal sensory systems.
According to Farmer, many parallels exist between plants and humans, and he believes there’s a common ancestor in the evolutionary line.
Plants also communicate through the air. Just about every green plant has its own chemicals that alert other organisms. The article points out that the smell of cut grass is actually a danger signal for other plants.
As a class, watch “What Plants Talk About,” free online from PBS (run time is 53:10). Ask students to actively watch the documentary and take notes.
The program features experimental plant ecologist and University of Alberta professor JC Cahill, who argues that plants regularly interact in their complex lives. He’s studied plants all across the country to identify their “animal” behaviors, and some of that field work is shown in the documentary.
Have students discuss the documentary. Then assign a research essay on a plant that displays animal-like behaviors and/or has been proven to communicate. In addition to requiring at least four credible research sources, have the students include points and examples from both days of the lesson. You may choose to have all students work from the same essay title, such as “Proving That Plants Communicate.”
Bring students on a walk around the school grounds. Have students bring a writing tool and paper to record observations and (if desired) sketch different varieties of plants.
Have an outdoor conversation about the plant community, share your observations and try to identify the types of plants growing on school grounds.
Assess students’ notes, participation in class discussion and outdoor observations. In addition, assess the quality of students' research essays using an appropriate rubric.
Lesson Plan Source
Jason Papallo, Education World Social Media Editor
Las updated 10/06/2015.
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