Euphorbia mauritanica—golden spurge. The name "mauritanica" is a misnomer. Linnaeus, adopted the name from an earlier botanist, having no idean that the plant was from Southern Africa, about as far away from Mauretania, think Northern Morrocco, as you can get and still be in Africa. The "flower" in the photo is quite small, measuring approximately 5 mm. The plant photographed is from a private garden in Berkeley, CA.