Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4

Forests.--The principal forest trees are the oak, beech, ash, elm, walnut, cornel, poplar, pine and juniper. The oak is universal in the thickets, but large specimens are now rarely found. Magnificent forests of beech clothe the valleys of the higher Balkans and the Rilska Planina; the northern declivity of the Balkans is, in general, well wooded, but the southern slope is bare. The walnut and chestnut are mainly confined to eastern Rumelia. Conifers (Pinus silvestris, Picea excelsa, Pinus laricis, Pinus mughus) are rare in the Balkans, but abundant in the higher regions of the southern mountain group, where the Pinus peuce, otherwise peculiar to the Himalayas, also flourishes. The wild lilac forms a beautiful feature in the spring landscape. Wild fruit trees, such as the apple, pear and plum, are common. The vast forests of the middle ages disappeared under the supine Turkish adm