Medium to tall plant. Stiffly hairy or hairless with latex, stems erect, branched. The basal leaves pinnately lobed to deeply toothed and short stalked. Upper leaves lanceolate untoothed or slightly toothed, clasping the stem. Flowerheads clear bright blue 25 to 40 mm in leafy branched spikes, all florets rayed, the rays strap like with a toothed tip.

Blue sow-thistle (Cicerbita macrophylla) has similar mauve-blue 'dandelion' flowers on a tall plant. Cicerbita macrophylla has an ovate apical lobe and often a pair of lateral lobes, flattened achenes and a pappus (the 'thistledown' attached to the seed).

Rough grassy habitats, roadside verges, wasteland and railway verges.

July to October

Perennial

Widespread but infrequent in Britain, particularly further north.

Not common in Leicestershire and Rutland. In The Flora of Leicestershire (Primavesi & Evans) it was found in 16 of the 617 tetrads.

It was on the 2011 VC55 Rare Plant Register (Jeeves, 2011) but is not on the current RPR (Hall & Woodward, 2022); it is listed as 'data deficient' because it is not clear whether records are of introduced/escaped plants or natives.