This beautiful plant is endemic to Crete and grows high up in rock crevices, on cliffs and on old walls.
The flowers of Petromarula pinnata vary from a lovely blue to almost white with just a hint of blue. This plant is a member of the Campanulaceae (Bellflower) family.
Wall lettuce has a very short flowering period, and so you need to be in Crete in April or May to be reasonably sure of seeing it.
The plants shown on this page were photographed in Crete in early April.