Seasonal Wild Flowers

Cotton Thistle

Onopordum acanthium

Scotch Thistle

Asteraceae

July to September

It is found throughout the country except for parts of the

Northwest and the Southwest. It is patchy in the

Northeast.

See the BSBI distribution map for Cotton Thistle

It grows in fields, hedges and other waste areas, often

near habitation and often coastal.

It is an archaeophyte and has been in the UK since

the Iron Age

It is increasing, probably as a garden escape.

Cotton Thistle is a tall, grey, spiny, biennial herb,

growing up to 2.5m.

The flowerhead is up to 6cm and has ferociously

spiny bracts.

Florets are pale purple.

Prior to the flowerhead opening, the upper central

bracts are yellow.

Leaves have no stalks and are spiny.

Stems are substantially winged with triangular spines.

The whole plant is covered with cottony white down.

Cotton Thistle, sand dune, Suffolk

Flowerhead, pale purple florets

Immature flowerhead

Stems and leaves

Close-up of leaves

Close up of winged stem