Well not quite a flower but a pretty plant.
Anytime I come across a wall like this I am reminded of a poem.
‘Flower in the crannied wall’
By Alfred, Lord Tennyson (1809–1892)
FLOWER in the crannied wall,
I pluck you out of the crannies;—
Hold you here, root and all, in my hand,
Little flower—but if I could understand
What you are, root and all, and all in all,
I should know what God and man is.