In article , Edgar Davies
writes
For some time botanists have thought that the Sweet Potato in the
Pacific spread from South America in prehistoric times.

Are there any suspected cases of a reverse migration - that is plants
crossing from the old world, over the Pacific, to South America in
prehistoric times?

The Malva/Lavatera group is predominantly Mediterranean, extending to
Macaronesia, South Asia, Central Asia and northern Europe. There are two
disjunct elements - one species (Lavatera plebeia aka Malva australiana)
in Australia and a few species on islands off the Pacific coast of
California and Baja California. There are closely related to each other,
and to the widespread Eurasian Malva sylvestris. This may represent a
case of transpacific colonisation.

Pavonia hastata is present in South America and Australia (but is only
doubtfully native in Australia).
--
Stewart Robert Hinsley