Greater Knapweed

Foodplant / internal feeder
larva of Acanthiophilus helianthi feeds within capitulum of Centaurea scabiosa

In Great Britain and/or Ireland:
Foodplant / parasite
mostly hypophyllous sorus of Albugo tragopogonis var. tragopogonis parasitises live leaf of Centaurea scabiosa
Remarks: season: 6-9

Foodplant / parasite
sporangium of Bremia lactucae parasitises live Centaurea scabiosa
Other: unusual host/prey

Foodplant / internal feeder
larva of Chaetorellia loricata feeds within capitulum of Centaurea scabiosa
Other: sole host/prey

Foodplant / internal feeder
larva of Chaetostomella cylindrica feeds within capitulum of Centaurea scabiosa

Foodplant / parasite
Golovinomyces cichoracearum parasitises live Centaurea scabiosa

Plant / resting place / within
puparium of Melanagromyza dettmeri may be found in stem of Centaurea scabiosa

Foodplant / saprobe
immersed pseudothecium of Nodulosphaeria centaureae is saprobic on dead stem of Centaurea scabiosa

Foodplant / parasite
underground tuber of Orobanche elatior parasitises root of Centaurea scabiosa
Other: major host/prey

Foodplant / feeds on
Orthocephalus coriaceus feeds on Centaurea scabiosa

Plant / resting place / within
loose puparium of Phytomyza cinerea may be found in leaf-mine of Centaurea scabiosa
Other: sole host/prey

Foodplant / saprobe
erumpent apothecium of Pirottaea brevipila is saprobic on dead stem of Centaurea scabiosa
Remarks: season: 6

Foodplant / parasite
pycnium of Puccinia calcitrapae parasitises live Centaurea scabiosa
Other: minor host/prey

Foodplant / spot causer
usually hypophyllous colony of Ramularia anamorph of Ramularia triboutiana causes spots on live leaf of Centaurea scabiosa

Foodplant / saprobe
gregarious, black pycnidium of Rhabdospora coelomycetous anamorph of Rhabdospora coriacea is saprobic on dead, silvery-grey-spotted stem of Centaurea scabiosa

Foodplant / internal feeder
larva of Terellia ceratocera feeds within capitulum of Centaurea scabiosa
Other: sole host/prey

Foodplant / internal feeder
larva of Terellia colon feeds within capitulum of Centaurea scabiosa
Other: sole host/prey

Foodplant / internal feeder
larva of Terellia plagiata feeds within stem of Centaurea scabiosa
Other: sole host/prey

Foodplant / internal feeder
larva of Trupanea stellata feeds within capitulum of Centaurea scabiosa
Remarks: Other: uncertain

Foodplant / gall
larva of Urophora cuspidata causes gall of capitulum of Centaurea scabiosa
Other: sole host/prey

Foodplant / gall
larva of Urophora quadrifasciata causes gall of capitulum of Centaurea scabiosa

Perennials, 30–150 cm. Stems 1–several, branches ascending, glabrous to ± hirsute. Leaves minutely hispid, resin-gland-dotted; basal and proximal cauline petiolate, blades 10–25 cm, margins usually 1–2-pinnately divided into linear or oblong segments; mid and distal cauline smaller, entire or once dissected. Heads borne singly or few in open cymiform arrays, pedunculate. Involucres ovoid to hemispheric, becoming campanulate, 15–25 mm. Phyllaries: bodies dark green, ovate (outer) to oblong-lanceolate (inner), glabrous or finely arachnoid, margins and erect appendages black, ± fringed distally with slender teeth, inner phyllaries with brownish scarious, expanded, erose dissected appendages. Florets many; corollas reddish purple (white), those of sterile florets 35–40 mm, often conspicuously enlarged, those of fertile florets 20–25 mm. Cypselae brown, 4.5–5 mm, puberulent; pappi of many unequal stiff bristles, white, 4–5 mm. 2n = 20 (Russia), 40.

Centaurea scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea. It is native to Europe and bears purple flower heads.

Greater knapweed is found growing in dry grasslands, hedgerows and cliffs on lime-rich soil. Upright branched stems terminate in single thistle-like flowerheads, each having an outer ring of extended, purple-pink "ragged" bracts which form a crown around the central flowers. The plant has deeply dissected leaves which form a clump at the base.

This species is very valuable to bees. It is also a magnet for many species of butterfly. Among them is the marbled white.

This is the only known food plant for caterpillars of the Coleophoridae case-bearer moth Coleophora didymella. Centaurea scabiosa has been used in traditional herbal healing as either a vulnerary or an emollient.

The plant is sometimes confused with devils-bit scabious, however the leaves on this plant are arranged alternately, whereas in devils-bit they are opposite.