Petromarula pinnata or "Rock lettuce" in the gorge of Samaria
A very large bush of Petromarula
Petromarula pinnata (the name peromarula means 'rock or
stone lettuce' in Greek, referring to the delicious taste of
the leaves which were used in salads) is an endemic Cretan
flower growing in cliffs and walls.
There are some very interesting and detailed facts about Petromarula pinnata as well as botanical drawings here if you are interested