This brilliant plant is a Lampranthus, a member of the Ice plant family, Aizoaceae.
The name Lampranthus comes from the Greek for bright and flower (Lampros + Anthos) and they certainly live up to the name, being one of the most showy flowers in my garden in Spring through to Autumn. I have a bed containing about 10-15 plants closely packed and the many flowers they produce make a virtual carpet of yellow in their prime. They can thrive in near drought conditions, the hotter the better, and in bright sunshine you need sunglasses to keep the combined reflective glare from burning your retina. 🙂
The plant is a small shrub up to around 50 cm high (18 in) with succulent leaves and has multiple flowers each around 5cm (2 in) across.
(Click on image to open in a new window and click again to expand)In the Spring sunshine I had to have an exposure balance on my camera of -0.7 for this shot or the light reflecting off it would have obscured the stamen completely! 🙂