West Mill Lane, Small Dole, Henfield, W Sussex (footpath by stream leading to waterworks). Massively complicated to differentiate between Common and Chalk Knapweeds. Lots of explanations against the other images.

Chalk Knapweed (Centaurea debeauxii) (20/08/2023) West Mill Lane, Small Dole, Henfield, W Sussex (footpath by stream leading to waterworks). Massively complicated to differentiate between Common and Chalk Knapweeds. Lots of explanations against the other images.

Chalk Knapweed (Centaurea debeauxii) (20/08/2023) West Mill Lane, Small Dole, Henfield, W Sussex (footpath by stream leading to waterworks).

Tottington Wood, Small Dole, Henfield W Sussex (on waste ground hillock behind pond). Lanceolate dark bits of phyllaries showing the pale bases of the bracts as here is a defining feature. Common Knapweed has them more broadly triangular so you can't see the pale bases.

Chalk Knapweed (Centaurea debeauxii) (29/07/2021) Tottington Wood, Small Dole, Henfield W Sussex (on waste ground hillock behind pond). Lanceolate dark bits of phyllaries showing the pale bases of the bracts as here is a defining feature. Common Knapweed has them more broadly triangular so you can't see the pale bases.

West Mill Lane, Small Dole, Henfield, W Sussex. The leaflets below the flowers here are narrower than the leaflets of Common Knapweed.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. The leaflets below the flowers here are narrower than the leaflets of Common Knapweed.

Along footpath to rear of water treatment station leading to Henfield Road, Small Dole, Henfield, W Sussex.

Chalk Knapweed (Centaurea debeauxii) (01/09/2021) Along footpath to rear of water treatment station leading to Henfield Road, Small Dole, Henfield, W Sussex.

Tottington Wood, Small Dole, Henfield, W Sussex. This is an unusual one, it has quite wide black tips on the phyllaries but they are stunted so mch so that the green parts of the phyllaries are really obvious, and the lack of much widening of the peduncle all lead to it being Chalk Knapweed. But it could be a hybrid.

Chalk Knapweed (Centaurea debeauxii) (24/08/2021) Tottington Wood, Small Dole, Henfield, W Sussex. This is an unusual one, it has quite wide black tips on the phyllaries but they are stunted so mch so that the green parts of the phyllaries are really obvious, and the lack of much widening of the peduncle all lead to it being Chalk Knapweed. But it could be a hybrid.

Chalk Knapweed (Centaurea debeauxii) (20/08/2023) West Mill Lane, Small Dole, Henfield, W Sussex (footpath by stream leading to waterworks).

Southbank Equestrian, Henfield (arena bank). Chuffed as sowed these from seed. Various sources say that Chalk Knapweed, despite the name, is often the one found in wildflower seed rather than Common Knapweed.

Chalk Knapweed (Centaurea debeauxii) (07/08/2023) Southbank Equestrian, Henfield (arena bank). Chuffed as sowed these from seed. Various sources say that Chalk Knapweed, despite the name, is often the one found in wildflower seed rather than Common Knapweed.

Southbank Equestrian, Henfield (arena bank). This specimen sown from seed does have quite a broadened capitula (normally that is a feature of Common Knapweed). But the shape of the phyllaries and the exposure of the green parts nevertheless point to Chalk.

Chalk Knapweed (Centaurea debeauxii) (07/08/2023) Southbank Equestrian, Henfield (arena bank). This specimen sown from seed does have quite a broadened capitula (normally that is a feature of Common Knapweed). But the shape of the phyllaries and the exposure of the green parts nevertheless point to Chalk.

Southbank Equestrian, Henfield (arena bank). This one has a really elongated involucre (the thing beneath the flower head). Some books say that Common Knapweed instead has a more globular involucre.

Chalk Knapweed (Centaurea debeauxii) (07/08/2023) Southbank Equestrian, Henfield (arena bank). This one has a really elongated involucre (the thing beneath the flower head). Some books say that Common Knapweed instead has a more globular involucre.

West Mill Lane, Small Dole, Henfield, W Sussex. Here you can see the narrow lanceolate nature of the leaves - Common has them broader.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. Here you can see the narrow lanceolate nature of the leaves - Common has them broader.

West Mill Lane, Small Dole, Henfield, W Sussex. Wildflowerfinder.org.uk says that Chalk Knapweed posesses auricles (on leaves mid-way down the stem) "a distinguishing feature" so I think this must be Chalk Knapweed.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. Wildflowerfinder.org.uk says that Chalk Knapweed posesses auricles (on leaves mid-way down the stem) "a distinguishing feature" so I think this must be Chalk Knapweed.

Tottington Wood, Small Dole, Henfield, W Sussex (on waste ground hillock behind pond). Also with auricles. Also less hairy than Common Knapweed.

Chalk Knapweed (Centaurea debeauxii) (29/07/2021) Tottington Wood, Small Dole, Henfield, W Sussex (on waste ground hillock behind pond). Also with auricles. Also less hairy than Common Knapweed.

West Mill Lane, Small Dole, Henfield, W Sussex. Stace says that Common Knapweed, and other sources on the Internet, have unlobed, or sparsely lobed, lower leaves, so these deeply lobed leaves are why I think this is Chalk Knapweed.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. Stace says that Common Knapweed, and other sources on the Internet, have unlobed, or sparsely lobed, lower leaves, so these deeply lobed leaves are why I think this is Chalk Knapweed.

West Mill Lane, Small Dole, Henfield, W Sussex. This is a leaf higher up the stem - narrow lanceolate. Common Knapweed instead has broader leaves. Also the latter is more hairy giving it a greyer appearance.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. This is a leaf higher up the stem - narrow lanceolate. Common Knapweed instead has broader leaves. Also the latter is more hairy giving it a greyer appearance.

West Mill Lane, Small Dole, Henfield, W Sussex. Yet another leaf, this one not as lobed as some of the others.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. Yet another leaf, this one not as lobed as some of the others.

West Mill Lane, Small Dole, Henfield, W Sussex. Showing the lanceolate leaves - Common Knapweed leaves are wider. This is a new flower bud.

Chalk Knapweed (Centaurea debeauxii) (03/07/2021) West Mill Lane, Small Dole, Henfield, W Sussex. Showing the lanceolate leaves - Common Knapweed leaves are wider. This is a new flower bud.