This Sow-thistle is widespread and common throughout the UK and Ireland.
There are many yellow members of the daisy family with flowers similar to those of the dandelion. The sow-thistles are easily distinguished by their spiny leaves.
The prickly sow-thistle, Sonchus asper, is similar but its leaves are generally greener and with sharper spines.
Smooth (or common) sow-thistle flowers first appear in May, but you may see this wildflower of wasteland and other disturbed ground blooming as late as November.
The plant on this page was photographed in West Wales in August.