RED STAR-THISTLE

Centaurea calcitrapa

Daisy & Dandelion Family [Asteraceae]

month8jul month8july month8aug month8sep month8sept

status
statusZarchaeophyte
flower
flower8mauve flower6purple
inner
inner8cream
inner
inner8indigo
morph
morph8actino
petals
petalsZ5
petals
petalsZMany
stem
stem8angular
stem
stem8ribbed
stem
stem8spines stem8thorns
contact
contactZlowish

29th June 2016, Chatham, Kent. Photo: © Paul Wright
Grows to 60cm tall but this specimen rather lifeless due to it experiencing drought conditions.


29th June 2016, Darland. Photo: © Paul Wright
Rather shrubby.


29th June 2016, Darland. Photo: © Paul Wright
Spend flower-heads with just their long almost-white, sharply-pointed phyllaries showing in a star shape.


29th June 2016, Darland. Photo: © Paul Wright
Only one head still in flower. Purple disc-florets with darker-purple or indigo tips.


29th June 2016, Darland. Photo: © Paul Wright
Darker-purple to indigo stigmas protrude from each 5-pointed disc-floret.


29th June 2016, Darland. Photo: © Paul Wright
The sharply-pointed and long phyllaries are one of the plants most identifying features, although two other Star-thistles (Yellow Star-thistle and Maltese Star-thistle) have similar ones, these are the largest (with the terminal spine being longer than 1cm) and longest of the three. Those on a fourth, Rough Star-thistle are far shorter, whilst those on a fifth, Lesser Star-thistle, lack any sort of spines.


29th June 2016, Darland. Photo: © Paul Wright
The upper leaves may be linear with a few teeth. Lower leaves may be deeply lobed.


29th June 2016, Darland. Photo: © Paul Wright
The spines are sharp!


Not to be semantically confused with : Starfruit (Damasonium alisma), Star-of-Persia (Allium cristophii), Star Sedge (Carex echinata), Starry Saxifrage (Saxifraga stellaris), Star-of-Bethlehem (Ornithogalum angustifolium) or any Star Moss [plants with similar names belonging to differing Families].

Some similarities to : Prickly Lettuce (Lactuca serriola) but that has yellow flowerheads which lack the very long yellowish star-like bracts beneath them.

More resemblance to : Yellow Star-thistle (Centaurea solstitialis) but that has yellow flowerheads and shorter and possibly more numerous yellow bracts beneath.

Uniquely identifiable characteristics

Distinguishing Feature :

Never extensive across the UK it now occupies ever fewer hectads, about 10 in the decade from 2000-2009, most being near the coast in West Sussex. Now a rarer plant, (2016) occupying but 8 or so hectads. It thought to be an archaeophyte having been possibly originally imported into the UK. It is a biennial.


  Centaurea calcitrapa  ⇐ Global Aspect ⇒ Asteraceae  

Distribution
 family8Daisy & Dandelion family8Asteraceae

 BSBI maps
genus8Centaurea
Centaurea
(Knapweeds)

RED STAR-THISTLE

Centaurea calcitrapa

Daisy & Dandelion Family [Asteraceae]