Daphne (plant)

Daphne species are shrubs, with upright or prostrate stems. Upright species may grow to 1.5 m (5 ft), with D. gnidium reported to 2 m,^[3] and D. bholua to 4 m.^[4] Their leaves are undivided, mostly arranged spirally or alternately (although opposite in D. genkwa), and have short petioles (stalks). The leaves tend to be clustered towards the end of the stems and are of different shapes, although always longer than wide. The leaf surface may be smooth (glabrous) or hairy.^[5][6][7]

Many species flower in late winter or very early spring. The flowers are grouped into clusters (inflorescences), either in the leaf axils towards the end of the stems or forming terminal heads. The inflorescences lack bracts. The individual flowers completely lack petals, and are formed by four (rarely five) petaloid sepals, tubular at the base with free lobes at the apex. They range in colour from white, greenish yellow or yellow to bright pink and purple. Most of the evergreen species have greenish flowers, while the deciduous species tend to have pink flowers. There are twice the number of stamens as sepals, usually eight, arranged in two series. Stamens either have short filaments or lack filaments altogether and are usually held inside the sepal tube. The style is short or absent, and the stigma is head-shaped (capitate).^[5][6][7]

The ovary has a single chamber (locule). The fruit is one-seeded, and is either a fleshy berry, or a dry and leathery drupe.^[7] When ripe the fruit is usually red or yellow, sometimes black.^[5][6]

The genus Daphne was first described by Carl Linnaeus in 1753 in Species Plantarum.^[1] Linnaeus included ten species, including Daphne mezereum, Daphne laureola and Daphne cneorum.^[8] Some of his species are now placed in other related genera (e.g. Linnaeus's Daphne thymelaea is now Thymelaea sanamunda).^[9] The type species of the genus is Daphne laureola.^[10] The number of species in the genus varies considerably between different authorities. The Flora of China states there are about 95 species, 41 of which are endemic to China, and the Euro+Med Plantbase accepts 21 species in the Western Palaearctic region.^[11] Some of these species were reduced to subspecies or varieties by Josef Halda in a series of papers from 1997 onwards,^[12] culminating in a monograph on the genus.^[13] Version 1.1 of The Plant List accepts 83 species.^[14]

Daphne is a Eurasian genus, being native to central and southern Europe and Asia,^[7] from Britain^[24] to Japan.^[25] Some species are also found in north Africa. A number of species have been introduced into other areas for cultivation, with two, D. mezereum and D. laureola, having become naturalised in North America.^[7]

Two species, Daphne bholua and Daphne papyracea, both called lokta, are harvested in Nepal and Bhutan for paper production.^[26]

Many species are cultivated as ornamental shrubs in gardens.^[27] The smaller species are used as rock garden plants or, in the case of those more difficult to grow, as plants for the alpine house. It is recommended that they are grown in well drained but moisture-retentive soil, avoiding strongly acid conditions. Most species prefer a sunny position, although some are woodland plants (e.g. D. mezereum and D. pontica). Propagation is by seed, cuttings or layering.^[5]

All parts of daphnes are toxic, the berries being particularly so. One active compound is daphnin, a glycoside, combining glucose with daphnetin. Some species have been shown to contain a further toxin, mezerein. Symptoms of ingestion include burning sensations and lesions of the mouth and upper digestive tract, gastroenteritis and diarrhoea, and in severe cases, damage to the kidneys (nephritis), irregular heart rhythm, and coma.^[36][37]

Daphnes have an OPALS allergy scale rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden.^[38] The sap and berry juice can cause dermatitis and the scent may affect the odor-sensitive.^[38]

• Variation in flower and fruit colour
• 
  Daphne blagayana
• 
  Daphne giraldii – unripe fruit
• 
  Daphne glomerata
• 
  Daphne gnidium – ripe fruit
• 
  Daphne jezoensis
• 
  Daphne jezoensis – ripe fruit
• 
  Daphne laureola
• 
  Daphne mezereum – deciduous
• 
  Daphne odora
• 
  Daphne petraea
• 
  Daphne pseudomezereum
• 
  Daphne × transatlantica Eternal Fragrance = 'Blafra'