PRICKLY SOW-THISTLE

ROUGH SOW-THISTLE

Sonchus asper

Daisy & Dandelion Family [Asteraceae]

Flowers:
month8apr month8april month8may month8jun month8june month8jul month8july month8aug month8sep month8sept month8oct month8nov

Pappus: pappusZpossible (white)
pappus8sep pappus8sept pappus8oct pappus8nov pappus8dec

status
statusZnative
 
flower
flower8yellow
 
morph
morph8actino
 
petals
petalsZMany
 
stem
stem8round
 
stem
stem8hollow
 
stem
stem8milkysap stem8milkylatex
 

24th May 2011, Worsley, Gtr Mcr. Photo: © RWD
Stout plant growing up to 1.5 metres it has narrow spiny glossy leaves and yellow Dandelion-type flowers.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Leaves narrower than those of Smooth Sow-Thistle, nor as deeply cut.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Leaves clasp the stem in a bending-over-backwards kind of fashion (un-like the almost right-angled clasp of Smooth Sow-Thistle.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Flowers a deeper shade of yellow than the much paler Smooth Sow-Thistle.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Flowers golden yellow, about an inch across.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Base of closed sepals bulges out into a vase shape when the seeds and pappus are developing.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Flower buds cylindrical when flower not yet opened (centre) and bulbous at the base when about to open in seed with parachutes.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Florets do not fade towards the periphery of the flower-head.


24th May 2011, Worsley, Gtr Mcr. Photo: © RWD
Very stout angular stem, with reddish streaks. Leaves with rounded auricles that are clasping the stem un-like Smooth Sow-Thistle.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Leaves not as deeply cut nor as broad as those of Smooth Sow-Thistle.


5th Sept 2010, Leeds & L/pool canal, Appley Bridge. Photo: © RWD
Instead, the leaves are not only doubly-toothed, but also crisped or wavy and spiny on the edges like they are in many thistles.


27th June 2009, Blackleach Country Pk, Walkden, Gtr M/cr. Photo: © RWD
A rather stout and tall example which has blushed red. Leaves rather more deeply cut than is usual, but retaining a fairly-wide and flattish mid-rib. Your Author considered the possibility that this specimen was the rare hybrid between Prickly Sow-thistle and Smooth Sow-Thistle, because like the hybrid, this specimen has rounded auricles but has lobed leaves (like those of Smooth Sow-Thistle) but lobed leaves do sometimes occur on Prickly Sow-thistle too.


Photo: © RWD
The stem is thick and angular.


27th June 2009, Blackleach Country Pk, Walkden, Gtr M/cr. Photo: © RWD
The leaves still have rounded auricles, but the main stem is so wide that the leaves auricles cannot sit astride the stem, as is usual.


4th July 2015, Leasowe Lighthouse, Merseyside Coast. Photo: © RWD
The seed head with white-haired pappus.


4th July 2015, Leasowe Lighthouse, Merseyside Coast. Photo: © RWD
The flattish seeds (achenes), at 2-3mm long, are slightly shorter than those of Smooth Sow-Thistle and usually have 3 thin ribs on each of two sides and two wing-like ones on the edges. (Your author guesses that the thinner ones are empty because those particular ex-florets were not fertilised?)


11th Aug 2015, arable fields, NW of Burscough Bridge, Lancs Photo: © RWD
The most diagnostic differentiating feature between the similar Smooth Sow-Thistle and Prickly Sow-thistle are that the leaves of the latter species have rounded auricles.


11th Aug 2015, arable fields, NW of Burscough Bridge, Lancs Photo: © RWD
A typical leaf curving over backwards with an auricle each side of the stem but the auricles are not pointed (as they are on Smooth Sow-Thistle) but rounded


Easily confused with : sub-species Sonchus asper subsp. glaucescens (but that only grows in two separated hectads on the Mid-Wales coast)

Hybridizes with : Smooth Sow-Thistle (Sonchus oleraceus) to produce Sonchus asper × glaucescens which apparently is very rare and is sterile (although it has a pappus with what look like seeds underneath, the seeds are not viable.

Easily confused with: Smooth Sow-Thistle, but that has pointed auricles whereas Prickly Sow-thistle sas rounded auricles which clasp the stem.

Some similarities to : Prickly Lettuce and Great Lettuce

Some resemblance to : Perennial Sow-thistle

The name Sonchus is derived from the Greek for 'hollow', the Sow-thistles have hollow stems, which, like many Sow-Thistles, contains a milky sap. .


  Sonchus asper  ⇐ Global Aspect ⇒ Asteraceae  

Distribution
 family8Daisy & Dandelion family8Asteraceae

 BSBI maps
genus8Sonchus
Sonchus
(Sow-Thistles)

PRICKLY SOW-THISTLE

ROUGH SOW-THISTLE

Sonchus asper

Daisy & Dandelion Family [Asteraceae]

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