Hello, lovers of all things green. Speaking of green, I often wondered what the lovely green growth that covers the pond in mid to late summer was. It turns out to be a Duckweed, a tiny wonder.
After sharing the sights and sounds of a campout on my screen porch last week, including the chorus of green frogs that lulled me to sleep, my friend Blaine Rothauser sent extraordinary photos.
One of them is a stunning trio of green frog friends. Another is the eyes of a green frog peeking through tiny leaves, which Blaine identified as Duckweed. It grows in our pond every year. I thought it might be an undesirable fungus, but after significant rainfall, the pond overflows into Johnsonburg Creek, clearing much of it. And while it always grows back, there’s plenty of life taking advantage of the pond. So, I concluded it’s nothing to worry about. It’s comforting to learn that Duckweed is beneficial to wildlife.
I have a funny memory from years ago of a black bear emerging when Miss Ellie and I were on our way over to the footbridge to cross over the pond on a late, overly hot September day. He gazed a us as if insensed that we interrupted his bath. Then shook off what I thought was algae. As the green stuff flew, I said aloud, ‘Shall I hand you a towel?’ Off Bubba Bear ran.
The Wonders of Duckweed
There are more benefits than harm to this unique floating aquatic plant sold for use in ponds and aquariums. It serves as a natural way to remove excess nutrients like phosphates and nitrates, to help control algae.
Native to most of the US and Canada and living in freshwater ponds and lakes all over the world, this remarkable plant is on the US Forest Service website as a Plant of the Week. They write that Common Duckweed (Lemna minor) is the smallest flowering plant known. Each plant is merely a quarter-inch tiny leaf, officially a modified stem, that floats on top of slow-moving ponds and lakes.
While walking over the footbridge yesterday, I noticed swaths of white amongst the green and wondered if they were in bloom. It turns out that Duckweed’s white flowers are so tiny that they are barely visible. They rarely bloom and therefore are hardly ever seen. Perhaps the white swaths I saw were the sun’s reflection on the tiny leaves or foliage in decline.
The flowers consist of two microscopic staminate flowers and one tiny pistillate flower in a pouch-like sac. Yet they attract flies, small spiders, mites, and even bees.
Duckweed is a Speedy Spreader
Duckweed primarily reproduces through clonal budding —an asexual reproduction process where a new plant develops from an outgrowth or bud of the parent plant. Common Duckweed can duplicate its biomass every two to four days and cover the body of water under favorable conditions. Ideal conditions are warm temperatures (50-90 degrees), part shade to full sun, but indirect sunlight, and nutrient-rich, slow-moving water. (Biomass means the total mass or weight of living and recently dead organic plant matter produced by a plant in an area or ecosystem.)
Maybe some think of the green cover of Duckweed as unsightly, but this green, by and large, is good. Duckweed provides shelter and food for fish, ducks, and aquatic life, as well as food for livestock, and is also a source of protein for humans. Already used in food in other parts of the world, manufacturers are looking into ways to include Duckweed in protein shakes, pasta, snacks, and baked goods.
There are more benefits of Duckweed than harm.
The presence of Duckweed indicates nutrient-rich water.
Other benefits include purifying wastewater by removing excess nitrogen and phosphorus, as well as cleaning out heavy metals. Duckweed can also impede the growth of harmful algae blooms. Plus, it helps keep the water cool.
In Devils Lake, North Dakota, the Lemma Wastewater Treatment Facility uses Duckweed for the final treatment of wastewater before discharging it into Creel Bay. “This all-natural system can treat approximately 3.5 million gallons of wastewater per day during the warmer months,” according to the City of Devil’s Lake.
Studies show that Duckweed (Lemna minor) effectively remediates municipal and industrial wastewater, removing over 84% of cadmium, copper, lead, and nickel. It also effectively removes arsenic.
What to do if Duckweed Covers a Pond
However, there is concern that if Duckweed fully covers a pond or lake, it can overshadow other aquatic plants, hindering photosynthesis and potentially impacting oxygen levels in the water. And, admittedly, I prefer some of the water visible in my pond. The remedy is as simple as using a pool skimmer to remove some of the Duckweed. Be careful not to take any critters with it. And you can then spread the green manure in the garden to enhance the soil—a beautiful thing. Indeed, green is good.
Mary Stone, owner of Stone Associates Landscape Design & Consulting.
As a Landscape Designer, I am grateful for the joy of helping others beautify their surroundings which often leads to sharing encouragement and life experiences. These relationships inspired my weekly column published in THE PRESS, 'Garden Dilemmas? Ask Mary', began in 2012.
I dream of growing the evolving community of readers into an interactive forum to share encouragement and support in Garden and Personal Recoveries -
seeking nature’s inspirations, stimulating growth, weeding undesirables, embracing the unexpected. Thank you for visiting! Mary
