Common knapweed

Common Knapweed

©Philip Precey

Common knapweed

+ -
Enw gwyddonol: Centaurea nigra
The tightly packed, thistle-like purple flower heads of common knapweed bloom on all kinds of grasslands. Also regularly called 'black knapweed, this plant attracts clouds of butterflies.

Top facts


Height: up to 1m

Conservation status


Pryd i'w gweld

June to September


Common knapweed, also known as 'black knapweed', is a thistle-like plant that can be found on all kinds of grasslands, from roadside verges to woodland rides, clifftops to lawns. It is in bloom from June to September and is a huge favourite of all kinds of butterflies, including common blues, marbled whites and meadow browns, and is sometimes covered in these species.

What to look for

The bright pink-purple 'flowers' of common kanpweed are actually composite flower heads made up of many small 'florets' (tiny flowers), surrounded by a crown of long, ragged, pink bracts (leaf-like structures). It has deeply divided, oblong leaves.

Where to find


Roeddech chi yn gwybod?

Due to its hardy and fast spreading nature, common knapweed is considered an invasive weed in North America.