This is some type of Euphorbia (the exact variety name is unknown to me as it was growing at my parents house when they bought it...20 years ago). It is a beautiful plant, cascading down rock walls, providing color and a neat texture all through the year. It almost looks like a plant that belongs underwater- don't you think?
I took a bunch of pictures out in my parents garden a couple nights ago. I love this garden in particular. The 'sundial' garden. I love it because this is what it looks like even in the dead of winter. I think so many people do not understand the importance of structure, form, and winter interest in their landscape! When people come in with landscape design questions, winter interest is the very first thing we address. It is what creates a 'base' or 'weight' for everything else that is planted.
During the summer, the corners overflow with white delphiniums.