Duckweed, Common duckweed
Lemna minor
Family: Lemnaceae
What it is like
Lemna minor is a PERENNIAL. See above for USDA hardiness. It is hardy to UK zone 4 and is not frost tender. It is in flower from June to July. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant). It is noted for attracting wildlife. Suitable pH: 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. Mesotrophic to eutrophic, quiet waters, in suboceanic, cool-temperate regions with relatively mild winters.
A cosmopolitan plant, found in most regions of the world, including Britain, absent from Tropics.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 1
Occasionally used as a vegetable. No further details are given but we have found the flavour to be less than desirable.
Medicine
Rating: 2
The whole plant is alterative, antipruritic, antiscorbutic, astringent, depurative, diuretic, febrifuge and soporific. It is used in the treatment of colds, measles, oedema and difficulty in urination. It is applied externally in the treatment of skin diseases and is used as a wash for ophthalmia. The plant is used in homeopathy, but the report gives no more details.
Alterative: Causes a gradual beneficial change in the body, usually through improved nutrition and elimination, without having any marked specific action.
Antirheumatic: Treats rheumatism.
Antiscorbutic: A plant rich in vitamin C that is used to counteract scurvy.
Astringent: Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.
Depurative: Eliminates toxins and purifies the system, especially the blood.
Diuretic: Acts on the kidneys, promoting the flow of urine.
Febrifuge: Reduces fevers.
Homeopathy: A plant used in homeopathic treatments.
Ophthalmic: Treats eye complaints.
Sedative: Gently calms, reducing nervousness, distress and irritation.
Skin: Plants used in miscellaneous treatments for the skin.
Other
Rating: 3
The dried plant repels mosquitoes.
Repellent: Plants that are said to deter but not necessarily kill various mammals, birds, insects etc.
Attracts Wildlife: Plants noted for attracting wildlife
Dynamic accumulator: Plants that gather minerals or nutrients from the soil and store them in a more bioavailable form and in high concentration in their tissues. Used as fertilizer or to improve mulch.
How it is grown
Requires a sunny position in still water that is rich in nitrates and lime. Duckweed can be a troublesome pond weed though it is easily controlled by simply scooping it out. This scooped out material makes an excellent addition to the compost heap. The growing plant is a good food source for fish and birds, as well as providing cover for creatures in the pond. Although it is towards the limit of its climatic range in Britain, it often flowers here if growing in a sheltered sunny position. It over-winters in temperate areas by means of resting buds which sink to the bottom of the pond in the late autumn and rise again in the spring.
Propagating it: Seed - we have no information on this species but, since it spreads so rapidly by division, it really needs no extra help once it is in a pond.
Best place to grow: Pond;
Habit: Perennial
Hardiness: 4-8
Growth:
Soil:
Shade: No shade
Moisture: Water