I gave my mother a well rooted cutting of either a Heptapleurum sp.
or a Schefflera sp. a couple of years ago, and it's lived through two
south-of-London winters outdoors without any sign of distress.

How can I tell which it is before I start telling you all the thing
is surprisingly hardy? (I think it's actually a Heptapleurum, as the
parent got to seven or eight feet high before I cut it down and was
inclined to bareness low down. But I'm not confident of my
judgement.)

Mike.