I deleted the original message before I remembered to respond, so maybe
I won't get to everything. Question 1, what is the difference between
paphs and phrags? Well, you can tell just by looking at the leaves. Or
I can... I can't say offhand what is different, phrags are usually more
conduplicate (folded in the middle) and the substance is different.
Tend to have more shine too. The roots are generally different, with
paphs having 'fuzzier' roots. This may be reflective of habitat, since
many phrags prefer a moister environment. There is a big difference in
the flowers, but the easiest one to see is if you cut open the ovary
transversely (in the short direction). Paphs have a tripartite ovary,
with the chambers non-distinct. In other words, one big kind of three
pointy space in the middle. Phrags have three distinct chambers. At
least I seem to remember that being one of the diagnostic features, a
taxonomist or somebody who has done slipper flasking more recently than
I will probably shoot me down.

Question 2, can you clone paphs and phrags? Interestingly, the answer
is yes. Or at least you can mericlone Phrag. Sedenii 'Blush' (published
in Die Orchideen quite some time ago, and repeated by Oak Hill), and
stem prop several different Paphs (anecdotally reported to me by a few
different growers who I have no reason to disbelieve). I've personally
cloned some Phrag Hanne Popow (starting from flasked material, but
still...). Mericloning paphs is not very successful. The limiting
factor for all slippers seems to be contamination, in that the meristems
are hard to get free of fungus. It can be done, but not in a reliable
fashion, and getting sufficient material to start often involves
destroying most or all of the growing points on the desired plant. The
growth media mericloning slippers hasn't been worked out, of course,
given all of the other problems. So, given that mericloning very rarely
works and is not unlikely to destroy the parent, it isn't really that
popular an option. It is a stated 'Holy Grail' of the slipper
community, but I suspect most people who actually make money selling and
breeding slippers would just as soon keep the status quo. You can get
more money for divisions if you can't make a lot of them.

Question 3. There is no question 3...

Question 4. Is there a difference besides the new world/ old world
distinction. Well, yes. See (1). But the big difference is that they
are group incompatible. You can't make Phragmipaphiums. There is one
(I think only one) registered, but it probably isn't a true hybrid. You
can't make Selenipaphiums, or Cypripaphiums either. Or at least not
that I've heard. That alone argues that they are different, and
substantially so. This may be (and I'm making s**t up here) due to the
evolutionary distance - the American continents split off from the
supercontinent a way long time ago, these plants have had plenty of time
to drift apart. They are certainly related, I don't think anybody will
argue with that, but the fact that they look similar is not really of
any consequence. And they aren't that similar, really, not if you have
seen a lot of each. Dendrobium phalaenopsis and Phalaenopsis amabile
are similar to the unitiated too, but they aren't very closely related.

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit