Camellia sinensis var. assamica is the tea variety that is associated with Assam, as the name attests.
I have also seen allusions and suggestions that this is the same as the "Da Ye" (large leaf) variety that is used in Yunnan for pu-erh and some red/black teas. Some tea merchants certainly describe their Yunnan teas as being from assamica plants, and the Assam jungles are not too far from Yunnan so this seems credible.
Is there a reliable source that confirms that the assamica variety is the same as the variety from which pu-erh tea is made? Or is the reality more complex, with most commercially grown pu-erh tea being a hybrid of var. assamica and other varieties?
Wikipedia pages about tea are currently poorly referenced and I tend to disregard most of the claims on the pages related to tea. I am looking for references to scholarly books, pointers to trade literature, credible news sites, or quotes from acknowledged experts.
(Note that I am not interested in growing tea plants, this is purely a question about provenance of the foodstuff.)