Duckweed

By Katie Finch, Senior Nature Educator

If you have ever explored outside with young children, you know there is a very good possibility that you will spend a lot of time looking at ordinary things. There are rocks on the trail you would not notice without children to point them out and plants you would otherwise pull out as weeds. Children see everything: worms, snails, slugs or a special stick that just has to go home with them.    

Audubon’s spring field trip season finished last week. From the end of April through the middle of June, over 1700 students explored the trails at Audubon. Audubon educators facilitated discoveries for another 1400 students in their schoolyards or neighborhood parks. There was a lot of looking at ordinary things.   

The thing is, what students discovered was not ordinary to them. Nature was real, interesting, and fun. “Ordinary” is just a perspective. As adults, if you change your perspective, it can make the ordinary appear extraordinary.

One of the ordinary things students ask about at ACNC is the green stuff that is floating on top of the ponds. Often we scoop up a little of it for students to look at closer. They notice it has leaves, but no stem. Roots that dangle down below the water. And it is tiny! It’s Common Duckweed.

If there was a competition for the most ordinary wetland plant, duckweed would win. Its range includes most of Canada and it has been found in every state except Hawaii and South Carolina. (This brings up a whole other question. Why not South Carolina?) Within its range, there is hardly a slow moving, freshwater body of water that doesn’t have duckweed in it. I decided to take a closer look into this commonplace plant.

Duckweeds belong to the genus Lemna. There nine species of duckweed in North America. Common Duckweed (Lemna minor) is the most widespread. Duckweeds are small, with leaves around ¼ of an inch long. In fact, they are the smallest flowering plants. Despite the small size, bees, flies and even spiders pollinate the flowers. They can also just bump up next to each other and pollinate each other.

Most of the reproduction of duckweeds does not happen because of flower pollination, which is called sexual reproduction. They more often reproduce by breaking off pieces of themselves. It is this method of reproduction, called asexual, that makes duckweed a very fast spreading plant. A colony of duckweed can double in size in two to three days in the summer. It often carpets the surface of a pond, causing viewers unfamiliar with the plant to wonder if they are looking at water or land.  

Because of this rapid growth, some sources call duckweed “an aggressive invader” or list it as an invasive plant. It can reduce oxygen and light in the water when it forms a solid mass. But, as the name suggests, it is food for ducks and other waterfowl and marsh birds. It also provides shelter for smaller insects and other invertebrates in the water.

Because of this rapid growth, some sources call duckweed an aggressive invader or invasive. It can reduce oxygen and light in the water when it forms a solid mass. Type “duckweed” into an internet search engine and half the websites that pop up are about removing it as a nuisance.

As the name suggests, it is also food for ducks, other waterfowl and marsh birds. Duckweed also provides shelter for small insects and other invertebrates in the water, which are then food for other aquatic animals. 

Duckweed’s rapid growth and commonness cause it to be very well studied. The DNA of several duckweed species is entirely mapped and sequenced. According the Department of Energy, knowing more about the duckweed DNA helps scientists study duckweed for many potential uses. Currently, scientists are asking a lot of questions about this plant. Would duckweed make good food for livestock? Could it be effectively used to produce ethanol fuel? How can it be used to clean up agricultural and municipal wastewater? Duckweed can take excess nitrogen, phosphate out of the water, reduce algae growth, and concentrate heavy metals.

It reminds me of snowflakes. Singly, they are insignificant. But they are something else when all together. Betty White, the famous actress and comedian said “Just consider one tiny snowflake alone, so delicate, so fragile, so ethereal. And yet, let a billion of them come together through the majestic force of nature, they can screw up a whole city.” I think something similar can be said about duckweed but instead of messing things up, duckweed might fix major problems.    

People often say “You are behaving like a child.” as an insult to point out bad behavior. But if I have learned anything from working with children it is that there are certain child-like behaviors we adults would do well to emulate. One of those is a sense of curiosity and wonder at the world around us, even in the ordinary things, like duckweed.

Audubon Community Nature Center builds and nurtures connections between people and nature. ACNC is located just east of Route 62 between Warren and Jamestown. The trails are open from dawn to dusk and birds of prey can be viewed anytime the trails are open. The Nature Center is open from 10 a.m. until 4:30 p.m. daily except Sunday when it opens at 1 p.m. More information can be found online at auduboncnc.org or by calling (716) 569-2345.