Easily confused with : other Corsican Hellebore and
Green Hellebore, but unlike Corsican Hellebore which has four protruding pods, Stinking Hellebore has but three. The leaves all also emerge from the stem. Oh, and it stinks!
Uniquely identifiable characteristics
More likely to be found in a garden than growing wild. When it does grow wild, it prefers limy soils in woodland or scrub.
Easily distinguishable from Green Hellebore (Helleborus viridis) in that : Green Hellebore lacks the maroon-tinged rims to the flowers, which are not cup-shaped or pendant, but (more open and out-facing), and the flowers are a lot greener (rather than pale green). The leaves on Green Hellebore, although deeply and multiply cut, have a circular profile (rather than a fan-shaped profile). Green Hellebore lacks a strong smell.
Although Stinking Hellebore does not smell all the timem, when it does it is said to smell of wet dogs, hence it's alternative name Setter-wort.
The five petal-like sepals may remain on the plant over-winter. They grow well in full sun and are drought tolerant. The nominally three nectaries (there can be up to ten) within the flower are modified hollow sepals (carpels) which hold nectar and yeast, the presence of which elevates their temperature above that of the ambient.
The roots of Stinking Hellebore contain the alkaloids
PseudoNervine and Veratridine and has similar medicinal properties as the much more poisonous Black Hellebore. Veratridine is a steroidal-derived alkaloid of the cevane series which acts as a neurotoxin, activating the sodium channels, leading to persistent activation and increased nerve excitation. It is used in ointments for the treatment of neuralgia and rheumatoid pain. Note the epoxy group bridging across between two fused rings, which is probably introducing strain and torsion in the fused rings. The epoxy bridge is probably easily broken at this oxygen atom, increasing the toxicity of Veratridine. It is based upon Imperialine.
This plant, like Helleborus niger, Helleborus orientalis, Helleborus lividus, Helleborus vesicarius, Helleborus dumetorium and Helleborus purpurescens (only some of which are native to the U.K.) contain bufadienolides (the main one being Hellebrin) saponins, and alkaloids such as
sprintilline. These latter two alkaloids have similar toxicity properties to Aconitine and
Veratrine but so far their structure is unknown.
It is deadly toxic, with the cardiac glycosides (bufodienolides) such as Hellebrin and bufadienolides such as the chemically related Hellebrigenin acting upon the heart and the steroidal saponins such as Helleborin and
Ranunculosides (sometimes known as Ranunculins) interfering with the digestive system. Ranunculosides are chemically similar to Coumarins (both are lactones). Symptoms of poisoning include nausea, vomiting, diarrhoea, headaches, mental confusion, numbness of extremities, hypotension, muscular spasms, cardiorespiratory failure and finally death. Some of the poisons can be absorbed through the skin.
Two more cardiotonic glycosides
Helleborein have in the past been administered for hypotension and heart failure but their use has now been discontinued for more reliable drugs.
Ranunculosides are contained in other members of the Buttercup Family such as Wood Anemone , Marsh Marigold, Globeflower, Pasque Flower,