published in the York Weekly, Portsmouth Herald, Fosters Daily, York County Coast Star 5/24/2021
My Integrated Earth Science class is immersed in its last unit of the year-the science of past and future climates and the mechanisms that underlie climate change. As an excuse to get outside I made up something called a Climate Change Impact Photo Scavenger Hunt. The idea was to go outside and take a picture of something that you think might be being impacted by climate change and then do a little research and find the climate change story. One of my classes really went crazy with photos of dandelions (the other class would have but I stupidly warned them away from dandelions believing them to be boring). Turns out, dandelions provide a terrific story about how human-caused climate change is affecting dandelion growth, one that applies to many other plants that tend to be ‘aggressive’ growers already, one that teaches a great lesson about the complexity of interactions between living things and a changing environment.
There have been a number of studies of dandelions in which researchers grew dandelions with elevated concentrations of carbon dioxide (twice current levels) and found that the increased CO2 caused the plants to produce more flowers and more seeds. The seeds were heavier and produced larger seedlings that grew more robustly. Then, in a study from Weed Science (“Reproduction of Dandelion (Taraxacum officinale) in a Higher CO2 Environment” 2007 by McPeek and Wang) I found this sentence “Furthermore, achenes from plants grown at elevated CO2 had characteristics, such as higher stalks at seed maturity, longer beaks, and larger pappi, which would increase the distance of seed dispersal by wind.” I love vocabulary-this was just great-achenes, beaks and pappi!
Plant Anatomy 101
One of my biggest regrets in life is that I did not like my college botany class and failed to absorb the wonderfully rich terminology used to describe the complexity of plants. If I had, I might have already known about achenes, beaks and pappi-terms I find confusing enough I am almost afraid to write about them. According to the Encyclopedia Britannica an achene is “a dry, one-seeded fruit lacking special seams that split to release the seed. The seed coat is attached to the thin, dry ovary wall (husk) by a short stalk, so that the seed is easily freed from the husk, as in buckwheat. The fruits of many plants in the buttercup family and the rose family are achenes.” Sunflower and dandelion seeds are also considered achenes. What this means is that each little feathery tendril of a puffy dandelion seedhead is an individual fruit. Each of those achenes is an individual ovary containing one seed that is attached to the feathery, helicoptery pappi by a long slender beak. If the beaks are longer and the pappi are larger, you have larger helicopters (or maybe parachutes? I’m not sure what to call them) that will help carry the seeds further afield. You put all of these enhanced traits together and you get dandelions on steroids, like the bionic man, they are bigger, stronger and faster. And so, the predictions are that they will thrive in future high CO2 environments.
Whether this enhanced proliferation of dandelions is good or bad is all relative and is dependent upon whether you think dandelions are awesome plants or the scourges of a manicured lawn. They were brought to this country by colonists who considered them medicinal powerhouses, curing all sorts of ailments most likely by providing needed vitamins. They are good for your lawn-they break up the soil and help aerate it. They are good for pollinators, a source of nectar that is available from spring through the fall.
In the end I wish I had encouraged everyone in my class to investigate dandelions from the start. What I found as students shared their reports about climate change and dandelions was that because dandelions are so familiar it was easy to connect to their climate change story, making the changes that are happening all around us more tangible, more real.
You can find more nature news (including informative nature minute videos about backyard nature) from me on Instagram @pikeshikes