Digitalis is the general genus with the wild native being Digitalis purpurea and is a species and Dalmation series is just a variety of the native one. They wont come true from seed. So lets say you have a pretty white one and collect the seed you may get totally different colours when they flower.
All the native ones will self-seed freely.

Too freely!

Thank you.I had wondered whether they would be sterile. I don't mind if they come up in other colours. I have bought several over the years but even if not eaten by slugs they have rarely survived for a second season.

once they have flowered and set seed they do die. They are biennials, so foliage year one then flowers & seeds year two and then death.

Thanks Sbg. I think I'll go for the native one in the hope of seedlings as it has not happened for me in the past. Lucky Owdboggy!