Back in March we make that trip to Kanapaho Gardens. As Jan, Anne and I got there we checked out the plants they had for sale, planning to get a few as we left. In the very back of the plants stood an old concrete urn full of rain water, old dead leaves, foul smelly dirt and the most luxurious growth of duckweed (Lemna minor) in the state.

We marveled at it so when bought plants later on, Anne asked about the duckweed and found it was not for sale. Turned out the garden folks knew nothing about the duckweed and said we could have it. What joy! In a plastic grocery bag I put five big handfuls of the wondrous greens and when I left, the urn looked just as weedy as when we first saw it.

We split the proceeds and at home I put half of mine into the bog attached to my pond. The other half went into a kiddies’ wading pool full of dead leaves, rancid dirt and mosquito larvae that had been sitting in my back yard for years. Not the most fastidious gardener, me.

The duckweed in the bog did poorly, did not multiply well. In short, it flopped and to this day it’s thin and sparse. This is the same result I have had with this plant for years. My fish love it and so I keep trying to grow it, but my pond does not support it. Meanwhile, back at the wading pool, there floated the second best crop of duckweed in the state. Hurray! Hurray!

Could it be the foul, leaf-laden water was better for the miraculous weed than the clear pond water that flows through the bog? Obviously so, which got me off on studying duckweed.

It turns out that this plant is a marvel of the vegetable kingdom. Given the right conditions, it can double its biomass in 24-48 hours, one of the fastest growing plants in the world. It propagates by budding so all plants in one population are clones or sister plants. Some Australian and African species have the smallest flowers and smallest fruits in the world. Smaller even than a grain of salt. It travels around stuck to the feet and feathers of birds. It also survives drying to the point of desiccation for weeks to months on end.

A voracious consumer of nutrients, duckweed is used to treat sewage and as a test plant for eco-toxicity. In short, if it is in the water the weed sucks it up. Which explains my problem with trying to grow it in the bog. My pond water flows through a 250 gal. up flow filter, an 8’x 8’x 3’ veggie filter with hyacinths (Eichhornia crassipes) and parrots feather (Myriophyllum aquaticum) and some of that water goes to a 10’x 4’x 10” bog with Anacharis (Elodea), more parrots feather and many other macro plants. The reason for all the foliage is to defeat green water. However, this is the same reason the duckweed does not grow in my bog. There are not enough free nutrients. Of course in the wading pool there is nothing but nutrients and no competition. Decaying plant matter and Florida sun make for a duckweed smorgasbord.

Then again, any body of still or slow moving water with sufficiently high nutrient levels will support a colony of the weed. And here we get another meaning of the word weed, a troublesome plant. Duckweed blooms plague many waterways about the country during summer months. These infestations foul the water, the shorelines and deplete oxygen levels.

Removing duckweed from lakes and ponds is either done with herbicides or by mechanical means. The herbicides do nothing about the nutrients in the water so repeated blooms are common. Not to mention the effect of chemicals on other plants and animals in the system.

Mechanical removal is a better choice as it also removes the nutrients. The weed can then be composted and fed to livestock. Duckweed is high in protein. Some studies show that one hectare of duckweed can supply enough food for over 4000 chickens and ducks. 10 acres of duckweed could supply over half the nutrients needed for 100 dairy cows. Then the cow manure can be used to fertilize more duckweed. Don’t you just love how nature works?