Help to ID this shrub

Some help to ID this shrub please.
It's from my place in zone 4a. The soil is very alkaline and it seems to be one of the first plants to break into the grassland. After a few years you'll often see another tree (cedar or choke cherry) poking out of the center of the cluster of stalks so it must be doing some important pioneering work.
One pic is early spring, the other is a few months later showing flowers. It's a beast if you let it get away from you and can take over a field in short order but if cut down to the ground the regrowth is so quick it makes a pretty good chop'n'drop plant.

That might be ninebark.

Wow.
You just may be right, I did some image searching and the Pacific Ninebark looks pretty darn close even though I'm east of the Great Lakes.
I'll look into the characteristics more as the season progresses.

THANK YOU.

I don't think it is the native Ninebark but a cultivar named Diablo (Physocarpus opulifolius, 'Diablo'). Still native, technically, but altered for color variety -- both leaves and seed heads. The seed head stage has those brilliant red clusters, but the flowers are only pinkish (more white than pink in the "uncomplicated" native variety). Here is a commercial site that has an interesting little page about it. http://georgeweigel.net/plant-of-the-week-profiles/flowering-shrubs/ninebark-diabolo

I don't recall it having the reddish leaves but I'll keep watching this as it changes with the seasons. I would call it invasive where we have it - or at least as alien as the grassy fields we're trying to keep it out of.