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Common Knapweed

©Philip Precey

Common knapweed

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Scientific name: 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

Stats

Height: up to 1m

Conservation status

Common.

When to see

June to September

About

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 knapweed 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

Widespread.

Habitats

Did you know?

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