Karyl Seppala has a great post on Ninebark at the Beautiful Wildlife Garden blog today. She is absolutely correct that the native Physocarpus opulifolius is a wonderful shrub: beautiful and useful to wildlife. And while cultivars of native plants have some challenges, in a designed landscape they can be indispensable.
There are many cultivars of Ninebark, but many share the same parentage. To keep them straight, I made a “family tree” of the most common ones. I find it helpful, and maybe you will too.