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Quercus ilex L., Evergreen Oak, Holm Oak

Account Summary

Introduced, neophyte, deliberately planted, very rare. Mediterranean, planted well beyond its native range.

15 October 1987; Waterman, T.; Inish Rath Island, Upper Lough Erne.

The fact that there is just one record in the Fermanagh Flora Database for this species does not accurately indicate the frequency of the tree in the county. Rather, it reflects the fact that local botanists have always ignored this dark foliaged, evergreen Mediterranean oak, since it is only ever present in Fermanagh as deliberately planted specimens in demesne parkland, large gardens and on driveways. I have no doubt that the tree on Inish Rath is also a planted specimen.

The New Atlas map shows Q. ilex in Ireland occurring extremely thinly scattered, almost exclusively on or near the coast. In Britain, by contrast, it is heavily concentrated in the area south of the Severn-Wash line, steadily declining and becoming increasingly coastal northwards, and rare in Scotland although it does stretch to an outlier on the extreme N coast in W Sutherland (VC 108).

Q. ilex seeds and regenerates freely in S & E England where it can aggressively invade natural habitats and threaten semi-natural vegetation with its very dark evergreen shade (T.D. Dines, in: Preston et al. 2002). However, even in Norfolk where the tree is especially abundant, in a local county survey James et al. (1981) found 87% of their Evergreen or Holm Oak sites were large gardens, estate parkland and churchyards. While the species grows to produce very large specimen trees in lawns and appears perfectly hardy around larger houses in the north of Ireland, as far as I am aware, the only place where it reportedly naturalises itself in Ireland, is in two sites in Co Waterford (H6) in the far south of the island (Green 2008).

Native occurrence

Q. ilex is prevalent from Portugal to Italy along the northern Mediterranean coastal belt, and from Morocco to Tunisia along the southern Mediterranean coast. There are two subspecies recognised; Q. ilex subsp. ilex is native on the northern shore of the Mediterranean from northern Iberia to Greece, and subsp. rotundifolia, is native in the SW of the species range from central and southern Iberia to NW Africa.

Holm Oak occurs in mixed species montane forests with Cedrus atlantica (Atlas Cedar) in the Atlas Mountains in Tunisia, Morocco and Algeria. While it can obviously tolerate existing conditions on slopes in the latter mountains, Q. ilex is generally confined to more definitely maritime situations, where it avoids cold continental winters. Holm Oak is introduced and grown in California.