|Helleborus niger, the so-called "Christmas rose", in the wild|
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (June 2011)|
Commonly known as hellebores[pronunciation?], members of the genus Helleborus comprise approximately 20 species of herbaceous or evergreen perennial flowering plants in the family Ranunculaceae, within which it gave its name to the tribe of Helleboreae. Many species are poisonous. Despite names such as "Christmas rose" and "Lenten rose", hellebores are not closely related to the rose family (Rosaceae).
Distribution and description
The genus is native to much of Europe, from western Great Britain, Spain and Portugal, eastward across the Mediterranean region and central Europe into Romania and Ukraine, and along the north coast of Turkey into the Caucasus. The greatest concentration of species occurs in the Balkans. One atypical species (H. thibetanus) comes from western China; another atypical species (H. vesicarius) inhabits a small area on the border between Turkey and Syria.
The flowers have five "petals" (actually sepals) surrounding a ring of small, cup-like nectaries (petals modified to hold nectar). The sepals do not fall as petals would, but remain on the plant, sometimes for many months. Recent research in Spain suggests that the persistence of the sepals contributes to the development of the seeds (Herrera 2005).
Species and subspecies
These four species have leaves on their flowering stems (in H. vesicarius the stems die back each year; it also has basal leaves).
- Helleborus argutifolius – Corsican hellebore
- Helleborus foetidus – stinking hellebore or setterwort
- Helleborus lividus
- Helleborus vesicarius
Acaulescent (stemless) species
These species have basal leaves. They have no true leaves on their flower stalks (although there are leafy bracts where the flower stalks branch).
- Helleborus atrorubens
- Helleborus croaticus
- Helleborus cyclophyllus
- Helleborus dumetorum
- Helleborus abruzzicus
- Helleborus liguricus
- Helleborus boconei
- Helleborus multifidus
- Helleborus multifidus subsp. hercegovinus
- Helleborus multifidus subsp. istriacus
- Helleborus multifidus subsp. multifidus
- Helleborus niger – Christmas rose or black hellebore
- Helleborus niger subsp. macranthus (syn. H. niger major)
- Helleborus niger subsp. niger
- Helleborus odorus
- Helleborus odorus subsp. laxus
- Helleborus odorus subsp. odorus
- Helleborus orientalis – Lenten rose, Lenten hellebore, oriental hellebore (N.B. most of the Lenten hellebores in gardens are now considered to be H. × hybridus)
- Helleborus orientalis subsp. abchasicus (syn. H. abchasicus)
- Helleborus orientalis subsp. guttatus
- Helleborus orientalis subsp. orientalis (syn. H. caucasicus, H. kochii)
- Helleborus purpurascens
- Helleborus thibetanus (syn. H. chinensis)
- Helleborus torquatus
- Helleborus viridis - green hellebore or bear's-foot
- Helleborus occidentalis (formerly H. viridis subsp. occidentalis)
Other species names (now considered invalid) may be encountered in older literature, including H. hyemalis, H. polychromus, H. ranunculinus, H. trifolius.
Hellebores are widely grown in gardens for decorative purposes. They are particularly valued by gardeners for their winter and early spring flowering period; the plants are surprisingly frost-resistant and many are evergreen. Many species of hellebore have green or greenish-purple flowers and are of limited garden value, although Corsican hellebore (H. argutifolius), a robust plant with pale green, cup-shaped flowers and attractive leathery foliage, is widely grown. So is stinking hellebore or setterwort (H. foetidus), which has drooping clusters of small, pale green, bell-shaped flowers, often edged with maroon, which contrasts with its dark evergreen foliage. H. foetidus 'Wester Flisk', with red-flushed flowers and flower stalks, is becoming popular, as are more recent selections with golden-yellow foliage.
The so-called Christmas rose (H. niger), a traditional cottage garden favourite, bears its pure white flowers (which often age to pink) in the depths of winter; large-flowered cultivars are available, as are pink-flowered and double-flowered selections.
The most popular hellebores for garden use, however, are undoubtedly H. orientalis and its colourful hybrids (H. × hybridus). They flower in early spring, around the period of Lent, and are often known as Lenten hellebores, oriental hellebores, or Lenten roses. They are excellent for bringing early colour to shady herbaceous borders and areas between deciduous shrubs and under trees.
Hybridising (deliberate and accidental) between H. orientalis and several other closely related species and subspecies has vastly improved the colour-range of the flowers, which now extends from slate grey, near-black, deep purple and plum, through rich red and pinks to yellow, white and green. The outer surface of the sepals is often green-tinged, and as the flower ages it usually becomes greener inside and out; individual flowers often remain on the plant for a month or more. The inner surface of each sepal may be marked with veins, or dotted or blotched with pink, red or purple. "Picotee" flowers, whose pale-coloured sepals have narrow margins of a darker colour, are much sought-after, as are those with dark nectaries which contrast with the outer sepals.
Recent breeding programmes have also created double-flowered and anemone-centred plants. Ironically, doing this is actually reversing the evolutionary process in which hellebores' true petals had been modified into nectaries; it is usually these nectaries which become the extra petals in double, semi-double and anemone-centred flowers. Double hellebores provide a very intesting variation to the standard hellebore. They are generally easy to maintain and share the same planting conditions as the standard hellebore.
Semi-double flowers have one or two extra rows of petals; doubles have more. Their inner petals are generally very like the outer ones in colour and patterning. They are often of a similar length and shape, though they may be slightly shorter and narrower, and some are attractively waved or ruffled. By contrast, anemone-centred flowers have, cupped within the five normal outer petals, a ring of much shorter, more curved extra petals (sometimes trumpet-shaped, intermediate in appearance between petals and nectaries), which may be a different colour from the outer petals. These short, extra petals (sometimes known as "petaloids") drop off after the flower has been pollinated, leaving an apparently single flower, whereas doubles and semi-doubles tend to retain their extra petals after pollination.
Gardeners and nurserymen have also created hybrids between less closely related species. The earliest was probably H. × nigercors, a cross between H. niger and H. argutifolius (formerly H. lividus subsp. corsicus or H. corsicus, hence the name) first made in 1931. H. × sternii, a cross between H. argutifolius and H. lividus, first exhibited in 1947, is named after the celebrated British plantsman Sir Frederick Stern. H. × ballardiae (H. niger crossed with H. lividus) and H. × ericsmithii (H. niger crossed with H. × sternii) similarly commemorate the noted British nursery owners Helen Ballard and Eric Smith. In recent years, Ashwood Nurseries (of Kingswinford in the English Midlands), already well known for its Ashwood Garden Hybrids (H. × hybridus singles, semi-doubles, doubles and anemone-centres), has created hybrids between H. niger and H. thibetanus (called H. 'Pink Ice'), and between H. niger and H. vesicarius (called H. 'Briar Rose'). The gardenworthiness of these hybrids has still to be proven.
Medicinal uses and toxicity
In the early days of medicine, two kinds of hellebore were recognized: black hellebore, which included various species of Helleborus, and white hellebore, now known as Veratrum album ("false hellebore"), which belongs to a different plant family, the Melanthiaceae. Although the latter plant is highly toxic, containing veratrine and the teratogens cyclopamine and jervine, it is believed to be the "hellebore" used by Hippocrates as a purgative.
"Black hellebore" was used by the ancients in paralysis, gout and other diseases, more particularly in insanity. "Black hellebore" is also toxic, causing tinnitus, vertigo, stupor, thirst, a feeling of suffocation, swelling of the tongue and throat, emesis (vomiting), and catharsis, bradycardia (slowing of the heart rate), and finally collapse and death from cardiac arrest. Although Helleborus niger (black hellebore) contains protoanemonin, or ranunculin, which has an acrid taste and can cause burning of the eyes, mouth and throat, oral ulceration, gastroenteritis and hematemesis, research in the 1970s showed that the roots of H. niger do not contain the cardiotoxic compounds helleborin, hellebrin, and helleborein that are responsible for the lethal reputation of "black hellebore". It seems that earlier studies may have used a commercial preparation containing a mixture of material from other species such as Helleborus viridis, green hellebore.
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In Greek mythology, Melampus of Pylos used hellebore to save the daughters of the king of Argos from a madness, induced by Dionysus, that caused them to run naked through the city, crying, weeping, and screaming.
During the Siege of Kirrha in 585 BC, hellebore was reportedly used by the Greek besiegers to poison the city's water supply. The defenders were subsequently so weakened by diarrhea that they were unable to defend the city from assault.
An overdose of medication containing hellebore has been suggested as a possible cause of the death of Alexander the Great.
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|Wikimedia Commons has media related to: Helleborus|
- Flora Europaea: Helleborus
- Flora of China: Helleborus
- Graham Rice & Elizabeth Strangman, The Gardener's Guide to Growing Hellebores, David & Charles/Timber Press (1993) ISBN 0-7153-9973-X
- Brian Mathew, Hellebores, Alpine Garden Society (1989) ISBN 0-900048-50-6
- Herrera, Carlos M. (2005). "Post-floral perianth functionality: contribution of persistent sepals to seed development in Helleborus foetidus (Ranunculaceae)". American Journal of Botany 92 (9): 1486–91. doi:10.3732/ajb.92.9.1486.
- Hellebores.org: A comprehensive online resource on the genus Helleborus
- RHS plant pathology report on 'Hellebore Black Death' disease (pdf)[dead link]
- A French hellebore enthusiast's non-commercial site
- Helleborus at National Center for Biotechnology Information (NCBI)
- Harvington Hellebores
- Artistic Movement, West Chester PA.
- A National Collection of Hellebores, Broadview Gardens (Kent, UK)
- A National Collection of Hellebores, Hazles Cross Farm Nursery (Staffordshire, UK) contains all known species plus hundreds of garden hybrids