Malus sylvestris (L.) Mill. s.l., Apple
Account Summary
Both native and introduced, occasional.
1976; Dawson, Miss N.; Muckross near Kesh.
March to November.
Since the Cultivated Apple, M. domestica and the native Crab Apple, M. sylvestris s.s. are often difficult or impossible to distinguish on an isolated field visit, there are a total of 44 records in the Fermanagh Flora Database of this non-commital taxon. When mapped, they show that almost all 30 tetrads in which they lie are on the shores of Upper and Lower Lough Erne. This is easily enough explained in that the records were frequently made by the members of the EHS Habitat Survey team during their survey looking for suitable conservation sites on the shores of both parts of Lough Erne in the 1986-9 period. There is also a definite habitat bias towards woods and hedgerows near water, including both riverbanks and lakeshores, again reflecting the lake survey.
Growth form and preferred habitats
In many areas of B & I, this densely branched, laurel-like, evergreen shrub or small tree grows up to 10 m in height with 15 cm long, glossy-leaves and small white flowers in erect racemes up to 12 cm in length, followed by 1 cm cherry-like, glossy red fruits that turn black as they ripen.
Since the middle of the 17th century, when the species was introduced from SE Asia and the Balkans, Cherry Laurel has been commonly planted in demesnes and large gardens, around building for shelter and as cover for game. It has slowly spread beyond these plantations and has become naturalised on woodland margins, along paths or in clearings, but occasionally it also appears on lakeshores and islands. In all these situations, it can form dense thickets and it has the potential to become as invasive and dominant over native species as Rhododendron ponticum (Rhododendron), particularly if the predicted rise in global temperatures results in its more frequent seed production.
Toxicity
As with P. padus (Bird Cherry), the leaves and the seeds within the fruits of P. laurocerasus contain cyanogenic glycosides (mainly prunasin and amygdalin). The fleshy part of the ripe fruit contains only very small amounts of these glycosides. In cut or crushed material of the species, the toxin is hydrolysed to form hydrocyanic acid that can starve animal tissues of oxygen, affecting the central nervous system and even causing death. The glycoside concentration is higher in young plants and during the summer (Cooper & Johnson 1998). Even hedge cuttings of the plant transported in a car to the local recycling centre can cause headache, nausea and mental confusion due to cyanide production by the cut material. This danger remains relatively unknown and needs to be made more public.
Fermanagh occurrence
Currently, in Fermanagh, there are records of P. laurocerasus from 31 lowland tetrads (5.9%) and in only a meagre handful of cases are the established plants outside estate boundaries or 'over the garden wall' and thus possibly self-sown and naturalised. Thus, the current author (RSF) suspects that many Fermanagh recorders have ignored or dismissed it as being 'a mere introduction', unworthy of note and, therefore, it is probably under-recorded.
Apart from a very few remote situations in Fermanagh in woods along the base of cliffs, this shrub has also been recorded on some wooded islands on Lough Erne, eg Crevinishaughy Island, just offshore of the Castle Archdale estate. Although, very possibly, it might be planted on these islands, escape from plantation sites may possibly involve not just vegetative propagation by means of the lower branches layering, a method of increase and dispersal that this species regularly employs, but transport of viable seed by birds. Webb (1982) has previously observed this circumstance on lake islands in Connemara. Nairn & Crowley (1998) reckoned that this shrub was so invasive and dominant in Co Wicklow oakwoods (H20) that it constituted a major threat to native species. In Co Waterford (H6), it has spread rapidly since first recorded in the 1950s and the majority of records are of self-sown trees (Green 2008). As yet this is certainly not the situation in Fermanagh.
British and Irish occurrence
The New Atlas map shows P. laurocerasus is much more frequent and widely scattered throughout B & I than was previously recorded, the calculated change index for the four decade period between the two BSBI flora atlases being as high as +4.7 (Perring & Walters 1976; Preston et al. 2002). Although widespread in Ireland, the records of P. laurocerasus show a definite southern and eastern bias in distribution, while in Britain the prevalence is very much more southern and western. Having said this, Cherry Laurel is also quite well represented, at least at the hexad level of discrimination, in lowland Scotland as far north as Inverness.
Threats
While in Fermanagh this invasive species is still mainly reproducing vegetatively by layering, occasionally Cherry Laurel sets seed. Were seed to become more frequent due to increasing summer temperatures, this species could quickly become as big a problem in local woodlands and other native vegetation as Rhododendron ponticum.