From my entire ignorance of Botany, I am sorry to say that I cannot answer any of the questions which you ask me.

I think I mention in my "Journal" that I found my old friend the southern beech (I cannot say positively which species), on the mountain-top, in southern parts of Chiloe and at level of sea in lat.

45 deg, in Chonos Archipelago.

Would not the southern end of Chiloe make a good division for you?
I presume, from the collection of Brydges and Anderson, Chiloe is pretty well-known, and southward begins a terra incognita.

I collected a few plants amongst the Chonos Islands.