It's not a virus. Helleborus niger can often produce green "staining" at the base of the petals/sepals. Generally it fades as the flowers age and become more of a faded rose color.

Wow, that green striping is gorgeous. So beautiful. I wish I can grow this niger specie of helleborus.

Thank you for the feedback. In more than thirty years growing H. niger and seeing it in other gardens, I've not come across the green markings. It was remarkable.

That is wonderful, geoforce! What kind of a growing environment does the H. niger prefer? I don't know what I did wrong last year but the two niger hellebore plants I bought from Burpees died by August while the other hybrids nearby were doing fine. I am trying again this year. Hope you or someone growing niger successfully can give me some advice on growing these well.

Most of my niger plants are in what would be called 'forrest edge' sites where they have high overhead shade and the only direct sun is early morning. Soil is very acid and with super drainage, but only so-so as to organic content and can get rather dry in summer. Many plants are directly at base of large trees (Lirodendron, Fraxinus and Nyssa) so have competition for resources.

I started with grown plants from 2 sources (1 local and 1 mailorder) and seed collected srom a plant seen in a nearby garden. From these they have now self sown and seedlings keep popping up all over the place, Probably have hundreds around and give away many which I dig out of unwanted areas. Seedlings are much slower developing that the H. X hybridus plants and seem to take 4-5 or more years to bloom.

Strange thing. Just happened to come across the link below which shows a trillium with green content similar to your secont photo of H. niger, Suspected to be a mycoplasma infection. Whether the same or, if so, what that means for the plant, I have no idea.

http://www.goldsword.com/sfarmer/Trillium/taylor.html

geoforce, thank you very much for sharing your experience. I will look for a good place with characteristics as you describe for my H. niger plant coming soon. The info you provided is very helpful. Thank you again.