Polygonum aviculare

  1. Wildlife
  2. Wildflowers
  3. Knotgrass


Common Knotgrass is found along the seashore, on waste ground, fields and roadside verges, and in gardens. This widespread plant has tiny, pale pink flowers that are very easy to miss as they appear so close to the stem; it blooms from May to October. Common Knotgrass is also known as 'Iron-grass' because of its tough, wiry roots that make it especially hard to pull up from the ground.

How to identify

Common Knotgrass has oval, leathery leaves of varying sizes, and tiny pink flowers that arise where the leaves join the stem.

Where to find it

Grows throughout the UK, but less common in the north-east of England and north-east of Scotland.


When to find it

  • May
  • June
  • July
  • August
  • September
  • October

How can people help

Although they sometimes don't look especially wildlife-friendly, our roadside verges, field edges and waste grounds can provide valuable habitats for all kinds of plants and animals. The Wildlife Trusts get involved in different projects to help make these places as beneficial for wildlife as possible. We have a vision of a 'Living Landscape': a network of habitats and wildlife corridors across town and country, which are good for both wildlife and people. You can support this greener vision for the future by joining your local Wildlife Trust.

Species information

Common name
Latin name
Polygonum aviculare
Height: up to 60cm but often grows horizontally
Conservation status