Photographed in April; growing abundantly on the side of a rocky path in Montserrat, Spain. Up to maybe 1 foot (30 cm) in height.
This plant is in the genus Euphorbia, which is a large and diverse group. The members take wildly different forms, but the general form of this plant is shared by many Euphorbia members. I'm not sure of the species, but think it is most likely Mediterranean Spurge, Euphorbia characias:
Photo: cc-by-sa-2.0 Bernard Dupont.