Lemna minor


The vast green mats that can sometimes be seen covering the surface of stagnant water are actually Common Duckweed. A familiar sight of freshwater ponds, flooded pits and old canals, this plant multiples by division and can easily overtake the surface of pool if left unchecked. As the name suggests, Common Duckweed does provide food for ducks, but it can also provide shelter for spawning Common Frogs and Common Toads.

How to identify

Each tiny, clover-like 'leaf' of Common Duckweed has a single root and is actually an entire plant - this simple structure is called a 'thallus'. Many of these tiny plants are packed closely together to create the yellow-green 'lawn' often seen on the water's surface.

Where to find it

Grows everywhere in the UK, but less common in the north of Scotland.


When to find it

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

How can people help

Human activity, including the drainage of land for agriculture and development, has resulted in the disappearance of many of the UK's wetlands. The Wildlife Trusts are working closely with planners, developers and farmers to ensure our wetlands are protected. You can help too: add native plants and flowers to a wildlife-friendly pond and its margins, and provide shelter for amphibians and nectar for insects. In partnership with the RHS, The Wildlife Trusts' Wild About Gardens initiative can help you plan your wildlife garden.

Species information

Common name
Latin name
Lemna minor
Diameter of individual plant: 1.5-5mm Root length: 15mm
Conservation status