Great Duckweed, Common duckmeat
Spirodela polyrrhiza

Family: Lemnaceae

What it is like

Spirodela polyrrhiza is a PERENNIAL at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. It is in flower in July. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant). Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It can grow in water.

Height (m): 0

Where it is found

Still water in ditches and ponds. Eutrophic, quiet waters, in temperate to tropical regions.

Europe, including Britain, south and east from Scandanavia to N. Africa and Asia. America, Australia

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 1

The plant is sometimes used as a food. No more details are given.

Medicine

Rating: 2

The whole plant is antipruritic, antipyretic, cardiotonic, carminative, diaphoretic, diuretic. It stimulates the appearance of measles rash. It is used in the treatment of colds, measles, oedema and difficulty in urination.

Antipruritic: Treats itching of the skin.

Antipyretic: Treats fevers. See Febrifuge.

Cardiotonic: A tonic for the heart.

Carminative: Reduces flatulence and expels gas from the intestines.

Diaphoretic: Induces perspiration.

Diuretic: Acts on the kidneys, promoting the flow of urine.

Other

Rating:

How it is grown

Requires a sunny position in still water that is rich in nitrates and lime. A very small plant without differentiation into various parts such as leaf, stem etc (they are called Thalli), it is 8mm in diameter and often forming a mat on the water surface and perennating by means of buds (turions) that sink in autumn and rise to the surface in spring. The so-called rootcap (really only an apical swelling), has a higher specific gravity than any other part of the plant, righting capsized individuals. The plant rarely flowers, spreading mainly by vegetative means.

Propagating it: The plant divides freely in the growing season and does not need help.

Best place to grow: Pond;

Habit: Perennial

Hardiness: 4-8

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Water

Things to keep in mind

Its other names

Local names

Synonyms

Lemna polyrhiza