Daphne laureola L., Spurge-laurel
Account Summary
Introduction, neophyte, either a very rare garden escape or deliberately planted.
3 March 1996; Northridge, R.H.; Flaxfield Wood, Castle Coole estate.
Growth form, English status and preferred habitats
This glossy, bright green, lanceolate, leathery-leaved, evergreen, low-growing shrub up to 100 cm tall is a native of sub-Mediterranean and sub-Atlantic regions. Some botanists suppose it is native also in copses and woods in parts of C & S England – despite the total absence of fossil evidence and its widespread cultivation from at least the 14th century onwards (Godwin 1975; Kent 1975; Harvey 1981). Even the first English record of the species in print refers to it being, "plētuously in hedges" (Turner 1548)!
Beyond the garden, Spurge-laurel typically, but often only locally, grows in deciduous woodland, on dry, near-neutral, lime or base-rich soils (hence its alternative common names 'Wood-laurel' and 'Copse-laurel'). The name 'laurel' is misleading as it is unrelated to other laurels of the genus Prunus in the Rosaceae. D. laureola is very shade tolerant and capable of spreading by layering, but it does not usually seed much, due to an absolute requirement for insect cross-pollination and an early vernal flowering season. On account of these properties and its limited invasive potential, very occasionally it is deliberately planted as pheasant cover on Irish landed estates, as appears to be the case in the deciduous woodland at Castle Coole, the solitary Fermanagh situation where this species has been found to date.
D. laureola occurs along with, or in similar situations to, other pheasant-rearing cover, eg the equally rarely found Ruscus aculeatus (Butcher's-broom) and the very common Symphoricarpos albus (Snowberry). Plants of D. laureola and R. aculeatus occasionally survive as scattered, isolated individuals, or more rarely as fairly large clonal patches, long after their introduction, when everyone who planted them is dead, and their human origins forgotten. It is easy to imagine this happening in England too, so that the so-called 'native' distribution has now become well and truly obscured by human, mammal- and bird-sown plantings (A.J. Richards, in: Preston et al. 2002).
Flowering reproduction
The flowers are produced from January to April and are sweetly scented for a period only. They are yellowish green in colour and hang in axillary raceme clusters of 5-10 flowers below terminal rosettes of glossy leaves. The calyx is 4-lobed, on top of a tubular hypanthium; petals absent; stamens eight; style solitary and short. Nectar is secreted and concealed at the base of the hypanthium tube and is accessible to bees, butterflies and moths (Melderis & Bangerter 1955; Hutchinson 1972; Sell & Murrell 2009).
The fruit is green at first, then bluish, and finally becomes a black, oval drupe up to 12 mm in diameter. Although the fleshy fruit is extremely poisonous to humans, livestock (including horses) and, indeed, possibly to all large mammals, it is taken by birds, including the Robin, and thus the seed can be bird-sown (Snow & Snow 1988, p. 94). Despite its toxicity (see below), the fruit may also be eaten by bank voles and mice, which therefore can also act as seed vectors (G.H. Knight, in: Lang 1987, p. 121).
Irish occurrence
Apart from Fermanagh, in other parts of Ireland D. laureola crops up as a rare or infrequent garden escape or discard, chiefly north of the political border, apart from on pheasant rearing estates. The plant usually occurs as isolated, presumably bird-sown individuals, in hedges, woods and in rocky places, or even rarely on old walls. Reynolds (2002) in her Cat Alien Pl Ir lists records of these types from nine Irish VCs, not including Fermanagh, and in some rare cases the shrub may become quite thoroughly naturalised.
British occurrence
D. laureola is locally frequent in England north to Cumberland (VC 70) and Co Durham (VC 66) and is present in N Wales in Pembrokshire (VC 45) and Glamorganshire (VC 41). It also is present in the Channel Islands. It is introduced in Scotland and the Isle of Man (New Atlas; Sell & Murrell 2009).
European and world occurrence
D. laureola is a submediterranean-subatlantic species that occurs from South-central and South Europe northwards into Hungary. It is also present in SW Asia and is rare in N Africa and the Azores (Sell & Murrell 2009).
Toxicity
Daphne species contain an acrid irritant sap in all parts of the plant, but particularly in the bark and the seeds within the berry-like drupes. Chemically, the toxins are described as tricyclic diterpenes with a daphnane carbon skeleton, daphnetoxin and its ester mezerein being the principal irritant compounds. Poisoning of stock animals is rare, as the plant is usually avoided because of its unpalatability. Only really starving animals would be tempted to try eating it (Cooper & Johnson 1998).
Human poisoning usually involves children who mistake the black berry-like fruits for currants. As the fruit is so very acrid, normally only a very few are eaten and the symptoms, which include a burning mouth sensation, nausea, abdominal pain, vomiting and diarrhoea, tend to be relatively mild and transient, although obviously frightening at the time for all concerned (Cooper & Johnson 1998).
Uses
D. laureola is less acrid than D. mezereum (Mezereon), and its leaves were formerly used an emmenagogue (ie to provoke menstruation), but they may cause vomiting and purging. Both leaves and bark have been used to induce abortion (Grieve 1931). It has been described as a brisk and rather severe purgative and was used as a cottage garden laxative. It was mixed with mistletoe and given for epilepsy. The crushed leaves were also reputed to have been used as a horse worming medicine although this was found to be dangerous and was discontinued due to fatal poisoning taken place (Cooper & Johnson 1998). The roots were also once used as a supposed cure for venereal disease and for treating both benign and malignant cancers. The latter use has scientific merit since it continues to be a subject of research (Allen & Hatfield 2004).
Threats
None.