Information on Knotgrass

Common Name: Knotgrass
Scientific Name: Polygonum aviculare
Irish Name: Gliúneach bheag
Family Group: Polygonaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Knotgrass could sometimes be confused with:

Knotgrass, Equal-leaved, Knotgrass, Ray's,

Sprawling, spreading across waste places, arable fields, roadsides and seashores, this plain, weedy, very variable, low growing – sometimes completely prostrate  - wildflower is best viewed through a hand-lens where its tiny little flowers come as quite a surprise.  When viewed closely, these small, white – sometimes pink - flowers (1-2mm across) have green centres and they emerge from leaf axils, sometimes solitarily, sometimes in small clusters.  They bloom from June to November.  The leaves are oval with the junction between them and the stem surrounded by an ochrea or papery sheath.  The stem leaves on this plant are larger than the leaves on the side branches.  This native plant is an annual and it belongs to the Polygonaceae family.   

I first identified this plant at Laragh, Co Wicklow in 1976 and photographed it at Ballyteigue Burrow, Co Wexford and The Rine, Co Clare in 2009.

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Knotgrass
Knotgrass

17th century herbalist and apothecary, Nicholas Culpeper, wrote of Knotgrass 'It is generally known so well that it needs no description' .  He goes on to say that 'Being boiled in wine and drank, it is profitable to those that are stung or bitten by venomous creatures'.   

In modern herbalism, Knotgrass is used to treat dysentery.  Also known in some parts as 'Bird-weed' this wildflower is much visited by seed-eating birds.