Helleborus niger 'Joseph (Josef) Lemper' is a selected seedling from a cross between 2 H. niger plants (unnamed), so it's entirely possible that it would produce viable seed.

Any seed produced though, would usually result in a plant unlike the hybrid parent, in some respects, but would still be a H. niger, since both parents were.

If there are viable seed, it might be interesting to determine what the plant appearance would be like!

Thanks very much, Georgia-rose. Planning on putting this in a new area, and letting nature do the work so we'll see what happens. I'm not sure how well it will do here since I am in Zone 8 (b-South Carolina). Have never tried a hellebore niger before, but now that they are more readily available, decided to give it a shot...also found 3 other Ivory prince plants at a different nursery and am going to try my luck with those as well. The hellebore orientalis and foetidus do very well here...almost too well...they seed around quite a bit (which suits me just fine...evergreen and deer resistant). Thanks again.

FWIW, it's been an outstanding plant for me since I planted it a year or two ago. Started blooming in November, and basically didn't stop through March.