Duckweed

Not just for ducks

Duckweed Lemma minor

• Duckweed is an oval shaped plant that floats on the surface of water

Duckweed Fronds

Roots

• Roots to 15 cm

• Reproduces by seed and vegetatively, thought during the growing season, nearly all plants arise by vegetative reproduction.

• Each duckweed frond contains buds from which more fronds may grow.

• Rapidly growing plants often have three or four attached fronds.

The air pockets of duckweeds provide buoyancy, much like the

air spaces in a rubber raft.

budding plant showing swollen underside with enlarged air spaces

(

Contact Pollination

Usually a Variety of Species

• Duckweed produces more protein per square meter than soybeans.

Duckweed can be used to feed fish, shrimp, poultry and cattle.

Duckweed can purify and concentrate nutrients from wastewater (sewage effluent).

Duckweed provides food for wildlife, especially waterfowl.

a duckweed treatment lagoon inside a plastic greenhouse. 

• Duckweed can be used as bioremediation in wastewater

Contain twice the protein, fat, nitrogen, and phosphorus of other

plants.

Can you name some biotic and abiotic factors

• that would influence the rate of growth of the duckweed in a pond or in the classroom?

• Light Fish

• Temperature pH

• Water amount rainfall

• Insects

• Which of the following growth curves do you think will illustrate the growth pattern of a small population of duckweed introduced into a container and left to grow for two weeks?

LAB: Effect of pH on Growing Duckweed

• You need to know what will help grow and what would hurt the duckweed

TIPS

• Duckweed spreads rapidly across quiet bodies of water rich in nutrients

• Grows best in water with high levels of nitrogen and phosphate.

• Iron is often limiting.

pH

• Can tolerate a wide pH range, but survives best between 4.5 and 7.5.

1-strong acid

2

3

4

5

6-weak acid

7-neutral

9-weak base

10

11

12

13

14-strong base

TIP

• Grows in full sunlight as well as dense shade.

• Can use fluorescent fixtures (cooler than direct sunlight)

BE CAREFUL

• Duckweed plants are delicate and easily damaged by fingers, forceps and other instruments. 

may be picked up and moved without damage using a bacteriological loop

Use Pond Water

• Or tap water that has been de-chlorinated

• And added Peter’s Liquid Fertilizer

GROW FOR 2 WEEKS

• Grow in a Petri Dish

• Different pH in each

• Add water if low

• Count fronds

• Record

• Graph

• Which pH is best?