Umbilicus rupestris, the navelwort, penny-pies or wall pennywort, is a fleshy, perennial, edible flowering plant in the stonecrop family Crassulaceae in the genus Umbilicus so named for its umbilicate (navel-like) leaves. In this photo the leaves look a bit shrivelled, probably because it has been hot and dry for so long. There must be very little water collecting in the cracks of this wall.