Prickly lettuce (wild lettuce)
Lactuca serriola (Lactuca saligna)

It has a hairless reddish stem, containing a milky latex, growing from 30 to 200 cm.

The leaves are oblong lanceolate, often pinnated (especially for the lower leaves), waxy grey green. Fine spines are along the edges. The undersides have whitish veins.
The flower heads are 11 to 13mm wide, are pale yellow, often tinged purple. The bracts are also often tinged purple. It flowers from July until September.
The achenes are grey, bristly tipped. The pappus is white with equal length hairs