So far as I understand, plants cultivated with human hand in a botanical garden, or any other garden/space for that matter, are not wild and hence not permissible on TN.
I removed a picture of mine posted some time back (and well received by fellow members) after coming to know of its ID from a knowledgeable member. The moment I realized that it could be construed as a cultivated plant by virtue of its name alone, I decided to remove it.
Rob Brown removed my lovely sunflowers last year which I had posted here on TN as a fresh and ignorant member :-)! It did hurt at that time until I read TOS.