I'm not sure if I've understood the last piece of your post correctly. I've never heard of lividus x orientalis before, but nothing is impossible these days in the world of hellebore hybridising. When you say orientalis, do you mean true species orientalis, or the plants still often being called H. orientalis hybrids but which should correctly be called H. x hybridus? It's not particularly relevant, I'm just curious...

Your post could be read in the way that you are looking for the ID of those hybrids. I'm not sure if that's what you mean though. I'm thinking probably not, as those plants would simply be H. lividus x H. orientalis (or H. x hybridus) hybrids.

The most up to date book is the Timber Press book, 'The Comprehensive Guide to Hellebores', by Cole Burrell and Judith Tyler. I think that you are probably looking for something more than that though... a foolproof book doesn't exist... yet. It would require many pages of leaves and flowers of all of the species. The classification is still in a major state of flux and a lot of work needs to be done in the field before anything along the lines of what you are looking for becomes available, although I don't think you will have to wait too long. Also, have you seen Joseph Woodard's site? Link below.

If you are growing a selection of acaulescent species, are they from wild collected seed with provenance? If not, a book will be pointless, no matter how good it is, as so called (acaulescent) species plants from cultivated seed should NOT carry the species name alone. At best they should be labelled as H. 'from torquatus' (for example).

Here is a link that might be useful: Joseph's site

Sorry, I got the address wrong for Joseph's site. Correct (I hope) link below.

Here is a link that might be useful: Joseph's site

Tim:

What a wonderful site Joseph Woodward has! Thank you for providing the link. I also noticed that he acknowledges someone named Tim Murphy in the site.... would that be you?
I thought I knew a fair amount about hellebores but I can see that I will be spending time on Joseph's site... as a starting point for researching those I am not familiar with. Thanks again for the link!

Sue
"The one thing all gardeners share in common is a belief in tomorrow"

Hello Sue, yeah, I am that same Tim Murphy...

I'm glad you like Joseph's site; it is the best source of information online at the moment.

I should make another correction to my original post. The title of the book by Cole Burrell and Judith Tyler is 'Hellebores, A Comprehensive Guide'.

Well Tim ... it is nice to make your celebrity aquaintance! Joseph speaks very highly of you in his website. I agree that it is sometimes difficult to give a definitive identification of uncontrolled seedlings even when most of the variables are known. Hopefully "Taxonomist" will find his answer.

Sue
"The one thing all gardeners share in common is a belief in tomorrow"