The actual posting wasn't the mistake, rather the fact that it was a group specifically for native plants of the northeast. H. vernalis and all it's cultivar incarnations really don't have any place in that group as even I'll admit it's not a true native. My mistake, and in future I'll try not to make it again.
Overall though it got a ton of likes, loves, and wow! (more than 50!) but in the comments one or two people weren't really having it. There wasn't any huge argument or anything like that. It was all quite civil but one comment struck me in particular. They commented something along the lines of "Just Don't" which is really dismissive, and I'll explain why in a moment.
Another comment though went as follows:
"It's a complex hybrid derived from mixed parentage including Hamamelis vernalis and Hamamelis x intermedia. Hamamelis x intermedia hybrids are crosses between Japanese witch hazel (H. japonica) and Chinese witch hazel (H. mollis). Basically not a true native"And they might be right. I actually don't know where either the nursery or the person commenting got their information from. Rare Find Nursery certainly sells a whole lot of H. x intermedia cultivars which suggests the plant farm they're getting their inventory from crosses a lot of different species. I'm sure I could inquire as to what makes a cultivar labeled as one species over another or how they control for contamination from one species, but I just don't feel like it right now. It seems like the kind of question that I might get different answers depending on who I ask too.
The real test though, in my eyes at least, is weather or not it's still used as a host plant to moths and butterflies.
Every other year now I've found at least one Azure butterfly laying eggs on the tree, and a few caterpillars nibbling at the flowers while being tended to by ants.
A number of these even make it to adulthood.
I don't believe I'm increasing the range of a species, rather offering an additional host plant for the species that were already here. I see Azures also using the Dogwoods and New Jersey Tea in my yard. (Azures are a complex though so it's unclear if it's just one species doing this or several.)
I'm hoping to do the same thing with Pawpaw trees and Zebra Swallowtails. Pawpaws are just barely native to NJ. There's a population all the way at the north of the state and then a very tiny one along the coast somewhere down south. But overall, Pawpaws are rarely found in NJ. It doesn't even come up on the Native Plant Finder for my area.
Witch Hazel is surprisingly host to a whole lot of species. According to the Native Plant Finder website, Witch Hazels in New Jersey are host to 128 species of moths, including the paddle caterpillar and unicorn which I've always wanted to see in person. This would be way more productive than Sourwood and Pawpaws combine.
For best results I should probably be planting H. virginiana but I see on the range and distribution for a lot of the moths that use it as a host do overlap with H. vernalis's range. It seems more than likely to me that a significant number would use both species as hosts regardless of what state they're in. The Native Plant Finder website does list a few moths that ONLY use H. virginana in NJ but that may be because they haven't had access to H. vernalis. Whatever the case I'm eager to see what, if anything, uses it. I may well turn out that my plant has genes from H. x intermedia in that that block it from being used by our indigenous Lepidoptera but I won't know unless I plant it and see.