Yes, i believe you are right...just looked it up and it looks just like it! Do these cluster? I hope so.

With a bit of luck. "Solitary or slowly clustering." Many pictures of big clusters if you google.

I saw that. I thought maybe they were seed grown and left in clusters.

Not usually with these larger types. You can see the heads growing out of each other in many cases.

That's a particularly nice flower. Have same, think you're right - reichenbachii.