In the South
It's easy to see what this duck has had for tea - a feed of duckweed.
Actually, just before the photograph was taken this duck was swimming in a pond that was completely covered in green duckweed. It was just swimming along with its head at water level and its bill open. Every so often it would close its bill and swallow. An easy meal!
Worldwide there are several closely related species of duckweed with the common New Zealand species ( Lemna minor) classed as a native plant.
Duckweed has no stems and no leaves. The floating green parts are sometimes called "fronds" but the correct name is thallus. Single roots grow from the thallus and these absorb nutrients from the water. Duckweed flowers infrequently and when it does it's said to be the world's smallest flowering plant.
It's an important food source for waterfowl and fish. An analysis has shown that duckweed has more nutrition by weight than any other flowering plant.
It's rich in fats, nitrogen and phosphorus. In several countries it's harvested for human consumption.
Duck weed also has an incredible growth rate. In favourable conditions the surface area covered by duckweed can double in less than two days.
No wonder ducks are attracted to ponds where duckweed is established.
- The Southland Times