A few years ago someone posted a picture of a plant they called Aruncus. I was excited because I had the same plant and didn't know the name. Now someone is wanting to know more about this plant and they are calling it Goats Beard. The leaves and bloom resemble my plant but it isn't the same. Can someone help me? Mine has long cups leaves and the blooms are more compact not feathery and the information states they grow to 6-feet in a shady environment whereas mine is over 12-feet and in full sun.

Thank you for any help you can provide.