Essex, United Kingdom

It was left by my house's previous owner. He had it in a pot. It doesn't seem to need watering and was moved it to the back of the garden where a wall collapsed and the earth delivers up a lot of stones and rubble if raked. It gets full sun in the summer and morning sun in the winter and has thrived. Height and spread around 60cms. Has beautiful white flowers that appear mid-late April. Its branches are very fragile and break off easily, and its growth very very slow. Leaf shape is reminiscent of a euphorbia, but I'm not convinced. Any ideas?

• 14 Apr, 2009