Wild lettuce (bitter lettuce, laitue vireuse, opium lettuce, poisonous lettuce)

Lactuca virosa

Lactuca virosa is biennial, similar to prickly lettuce Lactuca serriola but taller - it can grow to 200 cm (80 inches or almost 7 feet). It is also stouter, the stem and leaves are more purple flushed, the leaves are less divided, but more spreading.
The achene is purple black, without bristles at the tip. The pappus is the same as Lactuca serriola.
In the northern hemisphere, it flowers from July until September.