Looks like plumbago to me. There is also a white plumbago.

Scilla siberica, Siberian Squill and Puschkinia libanotica, Striped Squill.

Thanks for the ID, Tyrlych! Both "weeds" are nice looking plants. I had no idea that the Gibasis is a plant normally cultivated.

Sue it's a form of Euphorbia. It's a tiny cultivar of Euphorbia leucocephala http://www.burkesbackyard.com.au/fact-sheets/in-the-garden/flowering-plants-shrubs/euphorbia-leucocephala/#.VLoKL9KUddw and I think it's known in the trade as "Diamond Frost " or similar They can sucker, and they will die down over winter, when you can cut those canes right back and hopefully your plant will re-shoot in spring. Euphorbias like those have a white, latex-like sap which is an irritant so be careful handling it and keep kids and animals away if poss. Here is a link that might be useful: link