Prompted by a thread which flashed across my screen and then disappeared
I had a quick look at pelargoniums and geraniums.

The RHS say pelargoniums are tender, native to South Africa, and
commonly called geraniums. Wikipedia say they are both in the family
Geraniaceae and were originally both in the geranium species, but in
1789 pelargoniums were given a species name of their own.

My wild flower book says that Meadow Crane's-bill (geranium pratense),
Herb Robert (geranium robertianum), and Shining Crane's-bill (geranium
lucidum) are all in the Crane's-bill family (geraniaceae).

I suppose I have some five pelargonium varieties in my garden which
survive although I treat them as hardy and regard some of them as a bit
too robust (I have to prevent them taking over). I also have places
where I encourage the wild geraniums to grow. This is in the western end
of the weald in East Hampshire.

I was not aware until today that there was a taxonomic difference
between the plants known as pelargoniums, but commonly called
geraniums, and the wild native(?) geraniums.

--
Ellis Morgan