Leaf
Mathieu MENAND, Tela Botanica · CC BY-SA 2.0
Common knapweed
Centaurea nigra L.
Also known as: Black knapweed, Lesser knapweed, Hardheads
Family: Asteraceae
30 to 80 cm tall
Meadows, banks, track verges
Flowering: June – September
Full sun
Hardy to -15°C
❓ How do you recognise this plant?
The blackish, fringed bracts beneath the flower head give the species its name. Greater knapweed has large solitary flower heads with deeply cut outer florets spreading like rays, whereas common knapweed has smaller, rounder flower heads, with an involucre edged with clearly visible brown-black fringes.
🍃 Leaves
Lanceolate, entire to slightly toothed, somewhat rough
🌸 Flowers
Purple flower head surrounded by blackish fringed bracts
🍎 Fruits
Achenes topped with a small pappus
🪵 Bark
Upright, rigid herbaceous stem
🗺️ Distribution
Europe; very common in meadows and on banks in France.
🐝 Value for pollinators
Purple flower heads rich in nectar, among the plants most visited by meadow butterflies and bees.
✂️ Horticultural uses
Wildflower meadows, naturalistic borders; little grown in the conventional ornamental garden.
⚠️ Possible toxicity
No known toxicity.
⚠️ Look-alike species
Common knapweed
Centaurea nigra
Greater knapweed
Centaurea scabiosa
Greater knapweed has large solitary flower heads with deeply cut outer florets spreading like rays, whereas common knapweed has smaller, rounder flower heads, with an involucre edged with clearly visible brown-black fringes.
🌿 Other Asteraceae to discover
ℹ️ Educational profile — do not use it to judge whether a plant is edible or safe.
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