Common Knapweed (Centaurea nigra)

Common knapweed is one of the most familiar floral sights in the UK. With its habit and similar pink / purple crow its very close in appearance to a thistle and as such often mistaken for it. However it can be easily distinguished by its absence of spines and prickles.

Common knapweed is also known as black knapweed, ‘basket flower’ or ‘hardhead’. As the name ‘hardhead’ suggests this wildflower is one of our toughest, not only for its biological resilience but mainly its physical properties.  The spherical ‘hardhead’ of bracts (dark brown or black in appearance) which overlap each other like a tight pine cone are solid. It is the arrangement of the rigid basket-like cluster which sits underneath the flowerhead that also give it its name-  basket flower.

Photo credit: Aaron Matchett, Orangefield Park

Historically eligible young women would put a plucked unopened knapweed flower in their blouse. When the floret began to bloom it would suggest that the man of her dreams was near. Only in bloom from June to September meant that the rest of the year offered much less promise. The flowers 4cm in diameter are usually an inflorescence of the familiar pink / purple, but can be intense blue to more occasionally white. Its leaves arranged alternatively up the round and ribbed stiff stem are linear to lance-like in shape with incomplete lobes. Like the stem the leaves are covered in short stubbly hairs. 

The Royal Horticultural Society (RHS) has placed common knapweed on the RHS Perfect for Pollinators list, this means that it is a great nectar and pollen provider for a variety of insects, including bees, butterflies, beetles and flies. After pollination, the heads will attract birds that feed on the seed. It will also attract other small birds that want to feed on the bugs taking nectar from the flower head.

Where to find it?

Common knapweed is a grassland perennial so habitats include meadows, pastures, road verges, field borders, waste ground, scrub land and woodland edges. It can persist for many years in both grazed pasture and neglected grassland but in order to regenerate it needs an opportunity to set seed in open ground. As with many other flowers in our wildflower areas, they are reliant on maintenance to recreate suitable environments. Along the Greenway you can find them in all areas of wildflower, The Hollow, Marsh-wiggle Way, Flora Street, Loop River and Dixon Park. Our photographers have also found them in Orangefield Park.


Photo Credit: Aaron Matchett, Orangefield Park

Be Part of it…

With indications of summers end, (schools returning, nights darkening and a familiar chill apparent in the early mornings), we should make the most of our wonderful Greenway just before the summer season finally turns to autumn. We would encourage everyone to get out there! Whether it’s to cycle, walk or run, just take some time to look and around and observe all the peculiarities on your doorstep.