My earlier question has seemed to generate much confusion so I am taking a stab at re-writing it. Part of me fears that this board doesn't contain enough plant geeks (aka plant collectors), and perhaps it better suited for the American Public Garden Association but before I go there I hope others here might have experience with these plants.
We currently grow 5 species of deciduous stewartia and I have my eyes on another 3 or 4. However, I recently learned about the "evergreen" stewartia from the same 2008 Royal Horticulture article that @stormy linked to. Wikipedia suggests that some botanists classify the evergreen stewartia in the genus Hartia, so to avoid confusion I am going to call the group of plants I am interested in learning about Hartia.
The RHS article suggests that Hartia is not well know in the public garden sector, and has not been introduced into the nursery trade in either Europe or the US. The two articles above are my sole references to Hartia - I have found nothing in my 'common' references - Bean, Dirr, Rehder, etc, and was wondering if folks out there have come across references that talk about evergreen stewartia.
The second half of my question is a reach out the the gardening community to ask it anyone (especially in the US) is growing these plants. Poly Hill Arboreteum, the US national stewartia collection doesn't list any among their collections (dead or alive) under either genus. I haven't done a search of other major US arboreta, but I suspect nobody is growing this genus. If you are growing an evergreen steartia (Hartia) in your private garden, I would love to know how you heard about it, where you found it, etc.
If you are else where in the world and grow this genus, I would love to touch base. Perhaps there are issues with the genus that I'm not aware of that have prevented it from entering into the nursery trade.
Lastly, if there are any taxonomic geeks out there that would be willing to point me towards a better understanding of if I'm looking for the genus Stewartia or the genus Hartia that would most wonderful.