This seems to occur more and more. As taxonomy is developing there are more
and more species which occur across half the world but with lots of local
subspecies. If this continues then in twenty years a taxon at the rank of
species will be comparable to what used to be a genus or a section of a
genus.

Not sure if this is a good thing
PvR
+ + +

Cereoid+10 schreef
There are a number of subspecies of Rhipsalis baccifera found in Africa,
Madagascar and India. The species is also widespread in the New World
tropics where a number of subspecies can be found. There has been much
written on how the species might have found its way into the Old World
tropics.

Smith, G.F. & Steyn, E.M.A. (1997) Rhipsalis baccifera subsp. mauritiana:
the correct name for the indigenous southern African cactus. Bothalia 27
(2): 135, illus.

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Do you know which cactus is found in West Africa? Any theories on
how long it's been there?

Iris Cohen wrote
It's the one they call the tapeworm cactus. i think it's the Rhipsalis.
The seeds are sticky. The theory is that the seeds were carried across the
ocean by a bird. Dunno how long ago. Possibly prehistoric.

If I remember correctly, the red mangrove, Rhizophora mangle, has
floating
seeds which are immune to sal****er. I think they can even germinate in
the ocean. Conocarpus, which lives further inland, frequently has live
pieces
attached to chunks of very hard driftwood, which makes them highly prized
for bonsai. The tree can take salt spray, as far as I know. It is easy to
imagine pieces of buttonwood trees breaking off in a storm & floating across
the ocean.
Of course millions of years ago, Africa & South America were much closer
together. I read that the Florida peninsula is only 5000 years old, so
nearly all its plants came from somewhere else.
Iris