Hardy geraniums should not be confused with the frost-tender summer bedding geraniums, also known as pelargoniums. Geraniums (pelargonium) and hardy geraniums do belong to the same genus, Geraniaceae. But while pelargoniums and hardy geraniums are amongst the best perennials you can grow, they are not the same.
The first botanist to describe pelargoniums, when they arrived in Europe from South Africa in the 1700s, decided that in their basic structure they were similar to wild European cranesbills. Because the scientific name for cranesbills was ‘Geranium’, he called them Geranium africanum. Soon after, it was determined the two groups were sufficiently different for the African plants to have a name of their own – ‘Pelargonium’.
And there would never have been any confusion, had it not been for pioneer botanist Carl Linnaeus, who established the naming system that we use today. He called them all ‘Geranium’ and he was very influential, so the name stuck. So we now have two names for the same plants!