No relation to:
In the wild there are two subspecies: 'Christmas-rose': Helleborus niger subsp. macranthus (synonym Helleburus niger major) and Helleborus niger subsp. niger. Neither subspecies is native to the UK.
Cultivars abound: The most common cultivar in the UK is called 'Potters Wheel', first developed from seed in the 1950's, and the above photographs may be of that cultivar. Other cultivars are double-flowered.
Cultivated Hybrids include Helleborus × nigercors (Helleborus niger × Helleborus argutifolius). Several other hybrids between Black Hellebore and other Hellebores exist.
No relation to :
White Hellebore [which is now instead called
False Hellebore (Veratrum alba which is not a Hellebore but a plant belonging to the Herb-Paris Family (Melanthiaceae)].
Black Hellebore or Christmas-rose as it is more popularly known (since it flowers just after Christmas) is deadly poisonous, but no more so than most other Hellebores. The 'black' in its name refers to the roots, which are black. It is evergreen with large dark-green glossy pedate leaves on long stalks. The leaves are basal.
Black Hellebore has between three to five petal-like white (sometimes tinged pinkish or purplish) sepals. The sepals are rather irregular in outline, sometimes being pointed and yet other times radiused into a curve.
It is more likely to be found in a garden, for Black Hellebore is a cultivated plant. If it escapes into the wild as it sometimes does, it does not persist for more than a few seasons.
Like many members of the Buttercup Family it contains two toxic components: Ranunculin and Protoanemonin, but does not contain the cardiotoxic compounds Helleborin, Hellebrin nor
Helleborein that were previously thought to be present. It seems that those who analyzed the chemical composition of Black Hellebore had inadvertently got some
Green Hellebore mixed in with their samples! Green Hellebore (Helleborus viridis) does indeed contain these cardiotoxins, but not Black Hellebore.