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Celtic Wildflowers

ASTERACEAE

COMMON & CHALK KNAPWEED Centaurea nigra/debauxii

Knapweeds are native perennials growing 30-60 cm in height and produce purple flowers from June to August. The two most frequent species in our area are Common Knapweed and Chalk Knapweed (not restricted to chalky soils). The flowers of both species (which in some forms are rayed) attract large numbers and a wide diiversity of pollinator species.

Wildlife Value Rating
ProvenanceVC41 Glamorgan (Swansea) & VC44 Carmarthenshire
Fabian Way, Neath Port Talbot
Chalk Knapweed (unrayed form) with Shrill Carder Bee, Kenfig NNR, Bridgend
Chalk Knapweed (unrayed form) with Large Red Tailed Bumble Bee, Baglan Moors, Neath Port Talbot
Chalk Knapweed (rayed form) with Large Red Tailed Bumble Bee, Fabian Way, Neath Port Talbot
Habitats and Growing AdviceBoth of these closely related knapweed species can be important components of established grasslands in a wide range of habitats that includes pasture land, road verges, cliff tops, woodland margins and brownfield sites. They grow in light (sandy), medium (loamy) and heavy (clay) soils, preferring well-drained soils and even if nutritionally poor and are drought-tolerant. Once established, with appropriate management, they will self-seed and form strong populations capable of supporting large aggregations of pollinator species.
AssociationsThe 'Biological Records Centre’s' website lists the following numbers of foodplant associates for Common & Chalk Knapweed: mites (1) beetles (7), flies (16), true bugs (5), sawflies, wasps and bees (2), moths (25) and thrips (1). However, the genus Centaurea as a whole, lists the following: mites (1) beetles (11), flies (16), true bugs (5), sawflies, wasps and bees (2), moths (29) and thrips (1). Collectively plants belonging to the genus Centaurea are ecologically important for the diversity of invertebrates that they support, making them a must for any suitable project, large or small.
Orange-legged Flower-bee Halictus rubicundus is a species closely associated with Knapweed.
Orange-legged Flower-bee Halictus rubicundus is a species closely associated with Knapweed.
Stocklists for habitats