0tterbot wrote:
when people talk of a rockery or rock garden, what is it they mean? any
garden with rocks emerging above the surface, or is it more specific than
that?

Well, a rock garden can grow rocks; large isolated rocks. That is where
we puy all out rock samples we collect on trips.

A rock garden also meant a gardem mulched with rocks/pebbles. This
design becomes popular every so often, the dies again when people
realise that eventually you have to dig up and wash off those rocks
every so often[1]

similarly, if a plant is "good for rockeries", what does that mean? that it
drapes aesthetically over rocky bits, or is it a cultural notation? (wants
more heat & less water, or something like that?)

Yes. I take it to mean that plant either can tolerate or needs the extra
heat from rocks in the garden. Could also mean that it doesn't require
much soil, as in stuff that will grow onrock faces.

What is the plant?


[1] A previous owner of our place decided it was easier to just raise
the edges, buy more soil and rocks. So, one place in the garden provided
three layers of those 1"-2" river pebbles.