Herrera et al. (2010) studied the yeast communities established in the nectar of Helleborus foetidus, which is pollinated by bumblebees. Yeasts colonize H. foetidus floral nectar following probing of the nectaries by foraging bumble-bees carrying inocula on their mouthparts. Thus, the potential composition of yeast communities in the nectar can be estimated by examining the species composition of yeast inocula that are "‘travelling’" on the mouthparts of foraging bumblebees (i.e. the potential species pool). Herrera et al. compared this potential species pool with the actual yeast communities sampled from virgin nectar probed by bees. They found that only a small fraction of the potential species pool actually became established in nectar and that these species tended to be closely related. They suggested that this pattern is likely the result of H. foetidus nectar representing a harsh environment for most yeasts, such that only a few phylogenetically related nectar specialists physiologically endowed to tolerate a combination of high osmotic pressure and fungicidal compounds are able to develop.
Herrera et al. (2010) found that metabolic heat produced by nectarivorous (nectar-eating) yeasts alters the within-flower thermal environment of winter-blooming Helleborus foetidus. Flowers with yeast-containing nectaries had warmer interiors than flowers with "clean" nectar, and the magnitude of warming depended on the density of yeast populations in nectar. Although the authors did not directly evaluate the ecological consequences of yeast-induced floral warming of H. foetidus flowers in this study, they note that considerable circumstantial evidence suggests that some consequences are to be expected. Regardless of whether of it is produced by active endothermy or passive solar heating, previous studies have shown that floral warming can enhance plant reproduction through mechanisms that include increased pollinator visitation, pollen germination, pollen tube growth, fertilization success, fruit development, and seed size (Herrera et al. 2010 and references therein). Herrera et al. suggest that if the warming by yeasts of the interior of H. foetidus flowers raises the temperature of the gynoecium (female sex organs), then yeast warming could have beneficial effects on the maternal component of reproductive success, as found in other species. Warmth alone can act as a metabolic reward for pollinators and this effect is most likely under the cool conditions characteristic of the flowering season of H. foetidus (Herrera et al. 2010).
Helleborus foetidus, known variously as stinking hellebore /ˈhɛlɪbɔːr/, dungwort, setterwort and bear's foot, is a species of flowering plant in the buttercup family Ranunculaceae, native to the mountainous regions of Central and Southern Europe and Asia Minor. It is found wild in many parts of England, especially on limestone soil.
It is an evergreen perennial growing to 80 cm (31 in) tall and 100 cm (39 in) across, with a thick succulent stem and glossy leaves. The drooping cup-shaped flowers appear in spring, and are yellowish-green, often with a purple edge to the five petal-like sepals on strongly upright stems. The flowers, typically for the family, contain numerous stamens as well as up to ten nectaries which make them attractive to bees and other insects. Each flower produces up to five (usually three) wrinkled follicles. Despite its common name, it is not noticeably malodorous, although the foliage is pungent when crushed.[1]
All parts of the plant are poisonous, containing glycosides. Symptoms of intoxication include violent vomiting and delirium.[1]
Yeasts colonise the nectaries of stinking hellebore and their presence has been found to raise the temperature of the flower, which may aid in attracting pollinators to the flower by increasing the evaporation of volatile organic compounds. It was the first species in which this effect was discovered.[2][3]
H. foetidus is grown in gardens for its handsome evergreen foliage and large numbers of green, bell-shaped flowers borne in late winter. It prefers woodland conditions with deep, fertile, moist, humus rich, well-drained soil, and dappled shade. The species is, however, drought-tolerant. It often occurs naturally on chalk or limestone soils.
This plant has gained the Royal Horticultural Society's Award of Garden Merit.[4][5]
The cultivar 'Green Giant' has very bright green flowers and finely divided foliage; 'Miss Jekyll' has fragrant flowers, intensity varying with the time of day; 'Wester Flisk Group' has red-tinted leaves and stems and gray-green flowers; the 'Sierra Nevada Group' is dwarf, reaching 30 cm.
Propagation is by division or from seed, which can be prolific, naturalising well in ideal conditions. Rodents should be kept away from the garden since they depredate the seeds either when still in fruiting plants within the carpels or from the floor after seed release.[6]
Helleborus foetidus, known variously as stinking hellebore /ˈhɛlɪbɔːr/, dungwort, setterwort and bear's foot, is a species of flowering plant in the buttercup family Ranunculaceae, native to the mountainous regions of Central and Southern Europe and Asia Minor. It is found wild in many parts of England, especially on limestone soil.
