Distribution of the Common Oak
Owing to the general opinion of English botanists that there is only one indigenous species of oak, with two inconstant varieties, there are few accurate records of the distribution of the two species, and in the majority of cases it is impossible to say whether the specimens in our great herbaria are from wild or cultivated trees. Moreover, owing to the great changes caused by the spread of cultivation and the cutting down of most of the original woodland, the correct distribution of the two species can scarcely be made out. It is probable, however, that in ancient times the pedunculate oak occupied the alluvial lands and the better soils, now almost entirely devoted to agriculture and pasture. Hedgerow trees are invariably of this species. The sessile oak occupied the hilly land and the poorer soils; and in existing oak-woods occurring in such situations, which have never been touched by the plough, it is always the species met with, as in the Wyre Forest, the Forest of Dean, in the district about Burnham Beeches, in Lord Cowper's woods near Welwyn, Herts, which are on high-lying poor gravel soil, etc. In Scotland, judging from a specimen at Kew, the famous Birnam wood consisted of Quercus sessiliflora.[1] In Ireland, the ancient wood of Shillelagh, in Wicklow, of which a remnant still exists, was the same species. The Cratloe wood near Limerick is of pure sessile oak; and it is the only species in the wilder parts of Kerry. All the specimens of Q. pedunculata which I have received from Ireland, are from planted trees.
In England the oak ascends to 1200 feet in Yorkshire. In an interesting paper by H.B. Watt on the "Altitude of Forest Trees in the Cairngorm Mountains"[2] in Scotland, 700 to 800 feet is given as the highest level at which the oak was observed; but Mr. Watt says, in a MS. note, that he found in July 1903 a small oak at Corriemulzie at an elevation of 1200 feet. The same author gives many interesting particulars of the oak in Scotland, in a paper published in the Annals of the Andersonian Naturalists' Society, ii. 89 (1900). In Ireland the oak ascends in Derry to 1480 feet. There are remains of virgin forest in Donegal, on Sir Arthur Wallace's property near Lough Esk; and a very large oak wood, which is of great antiquity, occurs at Clonbrock, the seat of Lord Clonbrock, in Co. Galway, on the limestone formation. There are smaller woods in many of the mountain glens, and Mr. Welch of Belfast says that where these primitive bits of forest have never been touched by tillage, peculiar and local forms of land-shells occur, and the Clonbrock oak forest contains rare plants, moths, etc., unknown elsewhere. The oak was in early times much more widely spread; it has been found, e.g., in a peat moss in the Orkneys. Mr. T.T. Armistead[3] found a young oak growing in a sheltered ravine on the coast
