Duckweed: Not Just for Ducks

By Lee Lattimer

The Wood­land Trail takes the vis­i­tor to a pond that was, until the con­struc­tion of a dike in 2008, a sea­son­al wet­land. This now year-round pond is home to many frogs, drag­on­flies, tur­tles, and ducks. The green growth that cov­ers the pond’s sur­face might be mis­tak­en for algae. It’s actu­al­ly duck­weed (Lem­na spp,), a high-pro­tein food source for water­fowl con­sid­ered to be the small­est flow­er­ing plant in the world. 

Duck­weed is a very small free-float­ing plant that con­sists of one to three fronds, with a root (or root hair) pro­trud­ing from each frond. It forms dense colonies in qui­et water, often includ­ing more than a sin­gle species. This co-min­gling of species is indi­cat­ed by dif­fer­ent shades of green and is evi­dent in the Wood­land Pond.

One curi­ous aspect of the duck­weed is its abil­i­ty to with­stand dry con­di­tions or declin­ing tem­per­a­tures. Late sum­mer flow­er­ing pro­duces starch-filled struc­tures more dense than the fronds. The plants then sink to the bot­tom, become buried in the mud, and rise to the sur­face in spring. Thus one might con­sid­er the duck­weed a migra­to­ry plant!

Duck­weed is being explored for many prac­ti­cal uses. One is a form of ethanol. Duck­weed can dou­ble its mass every few days. By manip­u­lat­ing con­di­tions dur­ing its grow­ing peri­od, its starch con­tent can be increased and lat­er bro­ken down and fer­ment­ed into ethanol. Since duck­weed can be har­vest­ed reg­u­lar­ly, some­times dai­ly, it can pro­duce up to four times the ethanol per acre as corn. The use of ethanol does not increase the amount of car­bon in the atmos­phere. Since plants take in car­bon (in the form of CO2 ) as they are grow­ing, the car­bon released dur­ing burn­ing results in a net bal­ance, while fos­sil fuels cause a car­bon increase as they release car­bon that was once stored in the earth.

Duck­weed can also be used as a water puri­fi­er. As it grows, it has a sub­stan­tial need for nutri­ents, espe­cial­ly phos­phates and nitro­gen and ammo­nia. As the plant uptakes these ele­ments, it adds them to its bio­mass. This process fil­ters and cleans sewage and waste water. If tox­ic pol­lu­tants are not present, the duck­weed can be skimmed off and used for fer­til­iz­er or to feed fish. It can also be used to feed ani­mals, but a reten­tion peri­od in clean water is nec­es­sary to ensure that the bio­mass is free of water-borne pathogens.

The duck­weed is tru­ly a small plant with big poten­tial appli­ca­tions, thus prov­ing the old adage that good things come in small packages.


Fall 2016

Volume 34 , Number 4

Share this

The Latest from Landis

Mar 14, 2023

Picturing Landis through the year

Scenic Landis Arboretum just begs to be captured by photographers, professionals and amateurs alike. Enjoy... read more

Mar 14, 2023

2022 Annual Report

View or Download read more

Mar 14, 2023 | Nolan Marciniec

Re-thinking Garden Pests

“When we try to pick out anything by itself, we find it hitched to everything... read more

Mar 14, 2023 | Fred Lape, founder of the George Landis Arboretum

Barn Swallows

In this poem, Arboretum founder Fred Lape calls our attention to the “commonplace” miracle of... read more

Mar 14, 2023 | Anita Sanchez

Things Are Looking Up

Tree canopy -- Anita Sanchez Long ago I worked at a nature center, leading walks... read more

Mar 14, 2023 | Laurie Freeman

S-L-O-W Birding: A Primer for Beginners

Are you considering birding? Perhaps you’ve heard that birding is a great way to enjoy... read more

News Archive