Sue,
Clivia is the name of the genus. There are 5 species of clivia. Miniata (the only open type flower), Gardenii, Caulescense, Robusta and Mirabilis (the latter 4 all pendulous types.
The of course there are hybrids between the different species.
Hope this helps??

hello, dries, thanks. do they all grow to about the same size and do they all require the same treatment?

sue