Macleaya cordata

China and Japan. White Plume Poppy. Tough as old boots, great at the back of a border, sun any old thing… Tall   Abbie Jury has a bit to say about it. "It has an attractive blue-grey leaf that looks a bit like the plant version of cut-work embroidery. In spring and summer it shoots up stems to maybe two metres before flowering. True, the flowers are not exciting. More brown than gold, they look like seed heads even when they are in full bloom but they have a certain feathery charm while playing second fiddle to the more striking foliage. The problem is that it runs below ground, more like sprinting than running in some situations." They found, like me that in the shade or on rough pickings, it is more demure and manageable. I have planted it against a hedge, for me it has taken years to form a 2m wide patch, it looks amazing and nothing else thrives.  Do not plant in rich soils in the sun, unless you make a bund of some sort!  But in those tough spots out is perfect. Tiny little plants bursting to be planted. 

 https://jury.co.nz/tag/macleaya-cordata/   to see about romping away in the Jury paradise.