Seasonal Wild Flowers

Latin name

Centaurea macrocephala

Other names

Bighead Knapweed, Big Yellow Centaurea, Yellow Hardhat

Family

Asteraceae

Flowering season

July to September

English distribution

The escape is thinly scattered throughout the UK.

For a map see the Botanical Society of Britain and Ireland –

Giant Knapweed

Habitat

It is a neophyte that was introduced into the UK from the Caucasus

in the early 1800s and grown as a striking garden plant.

It has escaped into the wild and has been described as both a

noxious weed and a garden thug. However, it is not

clear that it is invasive in the UK.

It grows waste ground and relic gardens and orchards.

Description

Giant Knapweed is a perennial herb growing up to 120cm.

The flowerheads are up to 3.5cm across and are made up of

yellow florets.

There are rows of brown, fringed phyllaries below the florets.

The leaves vary in shape and size.
Basal leaves are oval with petioles and those up the stem

are narrow and run down the stem.

The stems are unbranched.