Bob, if you use the RHS plant search you can find the acceptable names for Helleborus.
A search for Helleborus orientalis brings up a list, by clicking on each you will get the information for each..
http://apps.rhs.org.uk/rhsplan...
A search for Helleborus niger ..
http://apps.rhs.org.uk/rhsplan...
A search for just Helleborus..
http://apps.rhs.org.uk/rhsplan...