Hellebore
Commonly known as hellebores, the Eurasian genus Helleborus consists of 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 hellebore species are poisonous.
Despite common names such as winter rose, Christmas rose, and Lenten rose, hellebores are not closely related to the rose family.
Etymology
The common name "hellebore" is first attested in 1300s; it originates, via Old French and Latin, ultimately from. Although traditionally translated as "plant eaten by fawns", this could be folk etymology and, according to Beekes, really a Pre-Greek word. It is not related to the word "hell", despite the toxic nature of this plant.In Anglo-Saxon England, the Anglo-Latin word elleborus had varied meanings. Around 900 AD, it was linked with "tunsingwyrt" in the Old English Herbarium. Ælfric of Eynsham seemed to assert that elleborus had no vernacular Old English translation; by the early 11th century, "wodewistle" was used to gloss the word, possibly referring to hemlock or similar. These shifts reflect the developing understanding of Latin plant names in Old English texts.
Description
The flowers have five petal-like sepals surrounding a ring of small, cup-like nectaries which are actually petals modified to hold nectar. The sepals do not fall as petals would, but remain on the plant, sometimes for many months. The persistence of the sepals may contribute to the development of the seeds.Taxonomy
The genus was established by Carl Linnaeus in volume one of his Species Plantarum in 1753.The scientific name Helleborus could derive from the Ancient Greek word , the common name for H. orientalis, constructed from and , "food.". It is also possibly from Greek, ἄλκη “fawn”, βιβρώσκω.
Species and subspecies
Twenty-two species are recognised and divided into six sections.The table below shows the species of the genus Helleborus, give its common name, the area of distribution, an image if available and the meaning of the scientific name. The cladogram shows the relationship between the different species determined with microbiological methods by Meiners et al..
Caulescent species
These four species have leaves on their flowering stems.- Helleborus argutifolius – Corsican hellebore
- Helleborus foetidus – stinking hellebore or setterwort
- Helleborus lividus
- ''Helleborus vesicarius''
Acaulescent (stemless) species
- Helleborus atrorubens
- Helleborus croaticus
- Helleborus cyclophyllus
- Helleborus dumetorum
- Helleborus abruzzicus
- Helleborus liguricus
- Helleborus bocconei
- 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
- * Helleborus niger subsp. niger
- Helleborus odorus
- * Helleborus odorus subsp. laxus
- * Helleborus odorus subsp. odorus
- Helleborus orientalis – Lenten rose, Lenten hellebore, oriental hellebore
- * Helleborus orientalis subsp. abchasicus
- * Helleborus orientalis subsp. guttatus
- * Helleborus orientalis subsp. orientalis
- Helleborus purpurascens
- Helleborus thibetanus
- Helleborus torquatus
- Helleborus viridis - green hellebore or bear's-foot
- Helleborus occidentalis
Hellebore hybrids
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-flowered hellebores provide a very interesting 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, which may be a different colour from the outer petals. These short, extra petals 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.
Interspecific hybrids
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 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 and H. × ericsmithii similarly commemorate the noted British nursery owners Helen Ballard and Eric Smith. In recent years, Ashwood Nurseries has created hybrids between H. niger and H. thibetanus, and between H. niger and H. vesicarius. The gardenworthiness of these hybrids has still to be proven.The following hellebore species and cultivars have gained the Royal Horticultural Society's Award of Garden Merit:
- H. argutifolius
- H. foetidus
- H. lividus
- H. niger
- H. × sternii 'Blackthorn Group'
- H. 'Walhero'
Distribution
Pests and diseases
Insects
''Phytomyza hellebori''
More commonly known as the Hellebore leaf miner, Phytomyza hellebori is a small fly that infests only the H. foetidus plants in the Hellebore genus. The leaf miner fly digs tunnels into the leaves of the H. foetidus. The tunnels create brownish-black blotches on the plant. These later turn into a nesting ground where the flies lay their eggs. With time, the leaves turn a brownish-white along where the tunnels were dug. The larvae start to eat the inside of the leaves in August, and damage develops from the late summer to the early spring, with heavy attacks leaving the foliage disfigured by spring.To control heavy infestations, the leaves can be removed and destroyed during the winter months before the adult flies emerge. Insecticides can be used with limited effectiveness in controlling larvae and fly populations in the plant. Insecticides may harm non-leaf miner flies if applied during the hellebore's flowering period.
''Macrosiphum hellebori''
Macrosiphum hellebori, commonly known as 'Hellebore aphid' or 'greenfly', is a sap-feeding aphid that infests the flowers and foliage of hellebore plants. The whitish-green aphids are about long and form dense colonies on hellebores, coating them with a honeydew that can lead to the growth of sooty mold on the leaves and flowers of the hellebore. This species of aphid only affects hellebores and is most active in March and April when the hellebores are flowering and when few aphid predators are around, though they may infest during any time of the year.Aphids start their feeding from the outside the flowers, beginning at the leaves and then moving towards the flower petals of the hellebore. As the hellebore begins to open, the aphids try to move into the flower. The aphids then feed on the inner parts of the plant as well as the young stems and shoots. As the population grows, the aphids eventually eat the remaining parts of the plant, such as older leaves, for food.
Aphid infestations can be controlled through persistent squashing of the aphids manually or by using insecticides. It is not recommended to spray flowering hellebores as it may harm the non-aphid pollinating insects.
Diseases
''Botrytis cinerea''
Botrytis cinerea or grey mold is a fungal disease that infects most ornamental plants. The fungus causes a decay of plant tissues and grows fuzzy gray-brown mold over the decaying areas, such as the buds, leaves, and flowers. Parts of the plant may shrivel and die after exposure to the mold, particularly the flowers. Typically the fungus infects plants only through an open wound or when the plant is under stress, but it has also been known to infect plants in humid conditions. If the humidity is low, the mold may be contained to discrete spots on the plant, but the mold has been known to spread rapidly in highly humid conditions. Grey mold is not seasonally dependent and can infect a plant at any time of the year. The fungus forms black seed-like structures in the dead plant tissue to create its spores to help it survive when new host plants are scarce. The spores are spread through the air to new plants.To treat the infected plant, the first step is to remove infected and dying leaves, buds, and flowers immediately along with any other dead plant materials around the hellebore. The next step is to reduce the humidity around the plant by improving the ventilation and ensuring the plants are not overcrowded.