Centaurea nigra

Centaurea nigra is a species of flowering plant in the daisy family known by the common names Lesser Knapweed, Common Knapweed and Black Knapweed. A local vernacular name is Hardheads.

It is native to Europe but it is known on other continents as an introduced species and often a noxious weed.

Description

It is a perennial herb growing up to about a metre in height.

The leaves are up to 25 centimetres long, usually deeply lobed, and hairy. The lower leaves are stalked, whilst the upper ones are stalkless.

The inflorescence contains a few flower heads, each a hemisphere of black or brown bristly phyllaries. The head bears many small bright purple flowers. The fruit is a tan, hairy achene 2 or 3 millimetres long, sometimes with a tiny, dark pappus. Flowers July until September. flowers sometimes are yellow, or white

Wildlife value

Important for Gatekeeper butterfly, Goldfinch, Honey bee, Large skipper, Lime-speck pug moth, Meadow Brown, Painted lady, Peacock, Red admiral, Small copper, Small skipper