Helleborus niger subsp. niger

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1964, Flora Europaea - Volume 1. Lycopodiaceae to Platanaceae, Cambridge University Press : 208

(a) Subsp. niger :

Leaf-segments oblong-cuneate, dark green, distinctly serrate near the top; perianth-segments often pinkish, broadly ovate. Throughout the range o f the species.