Smooth Sow-thistle

Smooth Sow-thistle

Observation - Smooth Sow-thistle - UK and Ireland. Description: Not in a park or garden but out of the pavement against a wall. About five inches tall with red (with purple tint) leaves and green blushes. Spaced points round edges of leaves. Yellow flower. Later in the year, I saw what appeared to be the same

Not in a park or garden but out of the pavement against a wall.

About five inches tall with red (with purple tint) leaves and green blushes. Spaced points round edges of leaves.

Yellow flower.

Later in the year, I saw what appeared to be the same kind of plant but much taller. It was ID-ed as Smooth Sow-thistle (Sonchus oleraceus). Is this a smooth sow-thistle that hasn't grown as tall, a different kind of sow-thistle - or not a sow-thistle?