I don’t have any precise locations myself as unfortunately I’m not living in that beautiful country. But that map is from a (long) article on peonies in Italy, “N. G. Passalacqua & L. Bernardo (2004) The genus Paeonia L. in Italy: taxonomic survey and revision, Webbia, 59:2, 215-268.” I suppose you have it, otherwise there would be no map, if not, contact me. The authors thereof have visited several locations where they grow naturally next to comparing herbarium collections. In the article those locations are more or less described (although in Italian), though rarely very precise. Perhaps if you can contact the authors they can tell you where to look? Perhaps they’ll invite you to their botanic garden where several officinalis peonies from different locations also grow. A quick search resulted in the following contact info:
Passalacqua Nicodemo Giuseppe (Curatore Responsabile dell’Orto Botanico)
e-mail: ni[email protected]
Bernardo Liliana (Professore Associato presso il Dipartimento di Biologia, Ecologia e Scienze della Terra)
Alternatively, there’s also a list in Hong De-Yuan’s book, but it’s not much different from the descriptive list in the aforementioned article. It usually shows where the herbarium samples were collected, but not very precise and with the collection date sometimes over a century ago, it can be expected that at some places they won’t be growing anymore and may instead flourish at other locations nowadays.
Another possibility might be to join a specialized paeonia species group on facebook, chances are quite high that some members there will know where to go. Those groups are ‘private’, but simpy request membership and they’ll normally let you join. My favorites are:
Hope this helps,
All the best,
Growing peonies for cutflowers in Belgium. Also hybridizing them.