Watermeal – A Fascinating Plant

Watermeal – A Fascinating Plant

One of the creative languages described in my R&D and creativity book is called a researching creator, I most resonate with the researching creator.  I also recently took a personality matrix test which said I was an ‘analyzer’.

Analyze, understand, sometimes publish, this is how my brain is wired, this how I like to create.

I think everyone should strive to be a constant learner.

This post is about a problem that we faced starting in 2013. This problem damaged the view in our back yard and it even killed the fish in our pond. The name of this problem is Wolffia Arrhiza (aka watermeal or duckweed).  No this is not a disease or a wild canine, it is a plant, and after studying this plant I think it is fascinating, this plant grows out of control on my property. This plant grows at alarming rates, I calculate that if conditions are right on my pond (and they usually are), it can reproduce over 100 pounds of itself in one day.

In 2013 this plant invaded and quickly covered the pond surface by the end of June, but the end of July dozens of my large fish had died from oxygen depletion in the water in the early morning hours. This watermeal flourishing on the surface of the water had choked out sunlight at the bottom of the pond, killing underwater plants which normally provide oxygen to the water.



This plant is a category of duckweed called Wolffia Arrhiza below are amazing facts about various duckweed breeds:

  • There are five breeds of duckweed.

5 duckweeds

  • Wolfia is the smallest plant on earth, the entire plant is only 1 to 1.5mm.


  • This plant can double in population in 4 days given the right water and wind conditions, meaning hundreds of pounds of vegetation growth per day on my <1 acre pond.
  • This plant thrives in stagnant warm water with high nutrients.
  • This plant has high starch levels which gives it potential for making ethanol.
  • Some Asian countries farm these plants to feed to chickens or goats
  • Some people around the world actually eat duckweed plants.


  • Rutgers University in New Jersey has a duckweed stock cooperative and does research on these interesting plants.
  • The RDSC collaborates closely with a second duckweed research project at Rutgers, an international effort led by the Waksman Institute of Microbiology, under the auspices of the US Department of Energy’s Joint Genome Initiative, to sequence the genome (~150 Mb) of the Greater Duckweed (Spirodela polyrhiza).The RDSC was established in 2009 with the acquisition of strains from the Biolex Corporation in NC, in addition to those collected by Todd Michael (then an assistant professor at Rutgers) and later from Professor Klaus Appenroth at the Friedrich-Schiller-Universität in Germany. As of October 2013, the RDSC has over 900 different strains, collected from all continents except Antarctica, and it continues to add to its collection.

Potential and Current Applications of Duckweeds

Several properties of duckweed make it highly attractive for environmental and agricultural applications:
  • Prolific growth on municipal sewage and agricultural runoff ➤ low-cost remediation of wastewater
  • Floats on water surface ➤ easily harvested (as opposed to algae)
  • High protein content (some strains) ➤ low-cost source of animal feed
  • High starch content (some strains) ➤ low-cost feedstock for biofuels and bioplastics
  • Low lignin content ➤ easy-to-process soft tissue

One reason why it’s such an efficient plant is that it doesn’t expend energy to grow a stem structure–it just floats on the water soaking up sunshine. Three small rootlets gather nutrients from the water, and three small leaves convert that into more duckweed. The roots don’t even have to gather water since the leaves lay flat on the water and can absorb water directly.

I’m also guessing that this enables duckweed to take up carbon dioxide at an accelerated rate since the solubility of carbon dioxide in water is seventy times greater than its solubility in air.

Our pond water is particularly high in nutrients due to four large willow trees which dump leaves and sticks into the pond almost year round. There are lots of different varieties of duckweed, some with leaves half an inch across, but the variety growing on my ponds is the smallest.

Research indicates that the smaller varieties of duckweed are more palatable to fish and humans; if we were growing duckweed to feed to our animals, we would probably want to work with a larger variety.

This problem has also been a learning opportunity.  This is a fascinating plant and I hope to invent a new use for it.