"Stewart Robert Hinsley" schreef in

This would be Harrington et al, Systematic Botany 30(2): 366-382 (2005)?
I see from the abstract that they propose merging Aceraceae and
Hippocastanaceae into a single subfamily.

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That looks right. In the discussion they state that the data allow either:
- splitting into five families or
- merging it into one big family
Both are feasible. They feel it is neater to make just one big family, but
it is mostly a matter of personal taste, or rather the APG-style, now in
vogue, of making big families.

I don't believe that this APG style is necessarily a good thing. To make the
order Malvales into the family Malvaceae is one thing, but the big family
Salicaceae looks to be riding for a fall.
PvR