Most people think of duckweed as a nuisance. Their tiny fronds, roughly a quarter of an inch, can form thick green mats that strangle other plants and litter motorboats. Cooperative Extensions at universities across the country publish resources about how to “control” duckweed populations.
When I think about duckweed, all I feel is wonder. Now, I am not saying we should let duckweed take over freshwater aquatic ecosystems. Rather, these unique plants have lessons to teach us about what it means to be a plant—and maybe even a human too. They warrant more than simply a passing glance.
Duckweed is the fastest growing flowering plant on Earth. However, the optimal combination of temperature, nutrients, and light needed to flower rarely occurs together. So duckweed more commonly reproduces through asexual budding. This growing technique is akin to a painting, eventually spreading across a freshwater pond canvas. Daughter fronds spiral out from the mother frond meristem, a clump of undifferentiated cells towards the center of the plant. The daughters develop over the course of one to two days, reaching between just a few millimeters to one centimeter in diameter. Daughters are attached to the mother frond by a stipe, a type of stalk, and remain attached to their mothers until they develop daughter fronds of their own. Once grand-daughter fronds begin developing, the stipe connecting the mother and daughter disconnects. The new mother-daughter pairing then floats away to continue growing in another part of the pond.
Duckweed will continue multiplying until there is no more physical space to grow into. When I see little families of duckweed clumped together, I cannot help but be reminded of the way people develop. Babies grow through a kind of stipe, an umbilical cord. Then they are born and completely rely on their parents. As the child grows up, maybe they’ll adventure across the pond. But we all spend our whole lives on the same pond, Mother Earth. Maybe we will one day float back to our parents, just like the daughter fronds when they float past their mothers.
Duckweed develops just like people, albeit over mere days instead of eighteen years. Just like people, the duckweed do what they want, when they want. For instance, when I set up an experiment in the lab, I reach into a flask to scoop up a group of duckweed. Often the duckweed swirl around the flask and evade my spoon. It feels like a test of willpower—who’s stronger, a PhD student or a tiny plant? Sometimes I wonder if the duckweed can sense my stress. They are forcing me to stop, take a breath, and regroup before continuing my experiment.
In the wild, duckweed continue growing until the physical space constrains it. People may try to control the duckweed population through physical, chemical, or biological means, but the reality is that the duckweed will grow wherever it wants. No human can tell duckweed what to do. But maybe I’m just spending too much time with duckweed.
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Art by Lara Schaberg
