Knapweed

Knapweed Studies

Centaurea calcitrapa RED STAR-THISTLE
Centaurea cyanus CORNFLOWER
Centaurea diluta LESSER STAR-THISTLE
Centaurea nigra HARDHEADS (=LESSER KNAPWEED)
Centaurea scabiosa GREATER KNAPWEED

Centaurea debeauxii CHALK KNAPWEED

Greater Knapweed Centaurea scabiosa	Lesser Knapweed (=Hardheads) Centaurea nigra	Chalk Knapweed Centaurea debeauxii
Purple flowerhead (sometimes pale and occasionally white). Rayed and larger (hence the name Greater) NB: when the flowers first appear the rays might not be there and later they often fall off.	Purple flowerhead, and much smaller than the Greater (hence the name Lesser). NB: occasionally rayed forms occur.
Bracts (involucre?) underneath the flower, larger and globose in shape.	Bracts (involucre?) underneath the flower, smaller and longer than wide in shape.
Leaves more substantial and the lower leaves are distinctive and different	Smaller leaves more regularly spaced up the stem right up to the bracts
Tall plant up to a metre and a half in height; a greater size.	Tall plant up to a metre in height but diminutive forms occur, ground hugging with a stem completely hidden

Lesser Knapweed (=Hardheads)
on the top of Mill Hill
Species under enquiry

6 September 2022

Red Star Thistle
Anchor Bottom

August 2022

Miniature Lesser Knapweeds on the lower slopes of Mill Hill

14 July 2022

Red Star Thistle
Anchor Bottom

8 July 2022

Lesser Knapweed (=Hardhead) at Old Shoreham Downs Link

2 August 2021

Greater Knapweed
Lower slopes of Mill Hill

28 June 2021

Greater Knapweed (white) and Knapweed Broomrape
Southern top part of Mill Hill

Greater Knapweed on Mill Hill (southern top)

22 July 2020

Greater Knapweed
Mill Hill, lower slopes

3 July 2019

Greater Knapweed
Mill Hill Upper, south of the Reservoir

11 July 2018

Mill Hill

5 July 2018

Mill Hill

1 November 2017

Greater Knapweed on Mill Hill (top)

25 October 2017
After the gales, a brief period of weak sunshine cast long shadows in the late afternoon, and I was pleasantly surprised to see an active Clouded Yellow Butterfly immediately on the upper meadow (north of the top car park) of MiIl Hill. Nectar plants were few and it was restless until it spent a second on the purple flower of one of the few remaining Greater Knapweed.

6 October 2017

Dead plants of mostly Lesser Knapweed
Verges of the Downs Link Cyclepath, south of the Cement Works

24 August 2017

The prostrate form of Hardheads are overall smaller than the usual upright plants. On less fertile shallower drier soil, this plant adopts a prostrate habit. It is still has a long stem and usually has a single flowerhead. The stem pushes its way through dense vegetation but lies upon or just above the ground, rather than being held erect

20 August 2017

Chalk Knapweed
Centaurea debeauxii
if this new species is accepted
Downs Link Cyclepath, Upper Beeding, Sussex. Very chalky. It could have an alluvium overlay. Inauthentic wildlife meadow, may have been seeded.