Daisy & Dandelion Family [Asteraceae] |
Flowers: |
Pappus: (short) |
status
flower
inner
morph
petals
stem
stem
sex
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Grows up to 4 feet tall, with branched rough stiff stems and rayed purple flowers. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
It is a dark-green plant rather than the greyish-green of the similar Common Knapweed which can also have flowers of the rayed form. Un-like Common Knapweed the stem leaves are narrow with narrow side-lobes. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Exists in rayed form only. Un-like Lesser Knapweed (now known as Chalk Knapweed (Centaurea debeauxii)) which has similarly coloured leaves, the head (actually the 'un-opened' flower bud) beneath the flower is spherical rather than Greek urn-shaped. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Like rayed versions of Common Knapweed but un-like Lesser Knapweed, the stems are swollen immediately below the dark spherical flower-bud. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
All Knapweeds consist entirely of disc florets; the long ray-like flowers on the outer edge of rayed versions are actually sterile and deeply cleft disc florets, cut into five strands. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Inner disc florets are a deeper purple, with white tips (these are fertile disc florets) |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
A Five-spot Burnet Moth atop. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Bird's-eye view. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
The bare spherical flower buds with deeply toothed brown to blackish 'phyllaries' and areas in-between looking like dark-green shields. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Lower stem leaves longer and with more narrow lobes. Stems rough with hairs. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Stems angled. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Upper stem leaves shorter and with fewer lobes. |
28th June 2011, Hightown, Sefton Coast. | Photo: © RWD |
Stems angled in places, with reddish-brown ridges on the edges. |
7th Aug 2016, unknown place. | Photo: © Ann Collier |
As with many plants, albino versions exist too, but are not frequent. |
7th Aug 2016, unknown place. | Photo: © Ann Collier |
It is not completely white; the petals are tinged slightly bluish-red whilst the stigmas are slightly yellowish-pink. |
7th Aug 2016, unknown place. | Photo: © Ann Collier |
The stigm of the top one is white and discoidal sitting directly on top of a yellowish-pink sheath. Perhaps the one alongside but to the right of that with the long rod protruding from the (on this one) split sheath is not a stigma but a stamen. But your Author is just guessing... |
26th June 2020, Safron Walden, Essex. | Photo: © Julia M. Smith |
Greater Knapweed is host to Greater-Knapweed Broomrape (known just as Knapweed Broomrape - in yellow or browned in the background). |
26th June 2020, Saffron Walden, Essex. | Photo: © Julia M. Smith |
Greater Knapweed is the only host to Knapweed Broomrape, no other Knapweeds will do. The leaves of Greater Knapweed are shown here with the broomrape right in the middle. |
26th June 2020, Saffron Walden, Essex. | Photo: © Julia M. Smith |
A closer view. |
Not to be semantically confused with: Common Centaury (Centaurium erythraea) nor with similar Centauries such as Seaside Centaury (Centaurium littorale) [plants whose scientific names are similar, but which are in a totally different Family altogether, the Gentian Family (Gentianaceae)]. Easily confused with : rayed versions of Common Knapweed but especially of Lesser Knapweed (now known as Chalk Knapweed (Centaurea debeauxii)). Easily mis-identified as : a rayed version of Lesser Knapweed(now known as Chalk Knapweed (Centaurea debeauxii)) but that has a Greek urn shaped 'head' or flower bud and leaves that have far fewer lobes, but rather with two auricles going part-way around each side of the stem.
Hybridizes with :
Not to be confused semantically with : Knotgrasses such as Knotgrass,
The Centaurea Genus encompasses many plants with thistle-like flowers (but not thistle-like stems or leaves), many of which have 'rays' on the outer edge which consist not of ray-florets (flat 'petals') but very long tubular disc-florets that have five deep clefts at the end, much like as those in Greater Knspweed, although not all are purple. Besides the Knapweeds, these include such plants as the sky-blue Cornflower, Perennial Cornflower and others that are not rayed such as Red Star-Thistle, Yellow Star-Thistle and Grows in grassy places especially on lime. Sometimes it is host to a parasitic plant called Knapweed Broomrape (Orobanche elatior) which specialises in being parasitic only on Greater Knapweed which may be several metres away, but connected underground.
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Centaurea | scabiosa | ⇐ Global Aspect ⇒ | Asteraceae |
Centaurea (Knapweeds) |
Daisy & Dandelion Family [Asteraceae] |