I consider a summer flowering ornamental successful in heavy clay under xeric conditions only if it can reseed itself (even make itself invasive). So far in 14 years I've found only 4 reliables--one is native and 3 are aliens: Sphaeralcea (globe mallow), Alcea (hollyhock), Malva sylvestris, and Taraxacum officinalis (dandelion). I've tried the stuff from nurseries that claim they're good for clay (but then you may find that doesn't mean under xeric conditions) and also tried to establish plants from seed I've gathered in wild areas. No luck. Anybody have suggestions for flowering and lasting perennials that have worked for you in these conditions?