One of the smallest plants in the world lives right here in the Midwest. It is called duckweed (Lemna minor). Not only is it a tough super-small plant, but its flower is also the smallest in the world with three white petals each the size of a pencil tip. To make the plant even more interesting and spectacular is the fact that it is a floating aquatic plant.
Each duckweed plant is very simple with no stems or real leaves. There is one tiny root per leaf. One to three identical round structures, which look like leaves, are actually just clusters of plant cells that contain chlorophyll and carry on the photosynthesis process of all green plants. Attached to each plant is a tiny air sac, which would be similar to us floating in the river with an inner tube. The air sac pops the plant to the surface when the water is disturbed. The mid-summer blooms produce microscopic seeds which form inside their own air sack. The seed floats away and are dispersed along the shore of still ponds and backwaters of the Mississippi River.
Though the plants are small they are mighty because of their vast numbers. Close to a thousand plants can occupy just one square foot of water surface. Multiply this by the large open bodies of water in the area and the numbers are staggering. So why make such a fuss about a little green floating plant? Why care about a plant that mixed in with other forms of algae and gives the backwaters a green slimy appearance?
Duckweed is a major food source and important part of a healthy eco system for all kinds of wildlife, ranging from fish, frogs and turtles in the water to ducks, geese and many other water fowl. It turns out that this inconspicuous plant contains more protein then soybeans. In parts of Southeast Asia, it is a food source for the people of the area.
Plants acts as a water filter system absorbing nitrates and other nutrients and chemicals that find their way into area streams and rivers. Oxygen is produced as part of the photosynthesis process aerating the water for all aquatic life. The cover produced by large numbers of duckweed also shade the surface cooling the water similar to us standing under a canopy of a tree on a hot sunny day. The list is endless of how all kinds of wildlife count on duckweed as an important part of their existence. In perfect environmental conditions it can be invasive for a short time.
Two other water plants which are more noticeable in the backwaters of the Mississippi are water lilies and lotus. These two water plants also play an important part of maintain a healthy eco system in bodies of still water. Waterlilies and lotus are from two separate plant families.
The White Waterlily or American Waterlily (Nymphaea ordata ) is winter hardy in this area. Roots and tubers grow deep into the bottom of shallow backwaters. These roots help to hold the muck and silt at the bottom of the rivers. The plants send stems 4 to 5 foot to the surface where leaves form. The leaves and flowers float on the water surface creating shade like the duckweed.
American Water Lotus (Nelumbo lutea) are often called water lilies because their similar appearance. Lotus however, have strong upright leaf and flower stems. Both can be seen growing above the water. This plant was a food source not only to all kinds of wildlife but to the Native Americans who lived in this area hundreds of years ago. Underwater tubers would grow as big as a human arm and would be roasted like sweet potatoes. The leaves were eaten like spinach and the seeds were used as nuts or ground into flour and stored for winter use.
All three of these aquatic plants can be seen in the backwaters of the Mississippi River by driving along the causeway to Lock and Dam 13 just north of Fulton, Illinois.
Margo Hansen is director of programs at Bickelhaupt Arboretum and the host of the Great Green Garden Show weekly on KROS Radio in Clinton.