An evergreen tree up to 60 ft high, with a trunk 5 ft in diameter, whose bark is remarkably thick and corky; young shoots covered with a close, grey down. Leaves oval, ovate or oblong, 1 to 21⁄2 in. long, 5⁄8 to 11⁄2 in. wide, rounded or abruptly tapered at both ends, toothed except near the base, upper surface dark glossy green, glabrous except when quite young; lower surface clothed with a minute grey felt; stalk 1⁄4 to 1⁄2 in. long, minutely downy. Fruits ripening the first year, borne singly or in pairs on a short, downy stalk.
Native of the west Mediterranean region; said to have been cultivated by the Duchess of Beaufort in 1699. The bark of this tree (which affords the best distinction between it and other evergreen oaks) produces the common cork of everyday use. It is stripped from the trunk and chief branches every eight or ten years. Portugal is the great centre of the cork industry.
var. occidentalis (Gay) Arcangeli Q. occidentalis Gay – In her work on the oaks, Mme Camus remarks that this is a physiological race of the cork oak rather than a distinct botanical variety or subspecies. It is found on the Atlantic side of Europe, from S.W. France through N.W. Spain and Portugal to W. Morocco, and differs chiefly in flowering more or less continuously. Fruits from the spring flowers ripen in autumn in the normal way, but ripening of the fruits from the later flowers is retarded by the winter and is not completed until the following summer or autumn. Another distinction is said to be that the old leaves usually drop as soon as the spring flush occurs, whereas in the normal form they persist for two or three years. The bark is only slightly thinner than in the normal form and is put to the same uses. This Atlantic race has proved to be much hardier than the Mediterranean cork oak and it is probable that the large trees growing in Britain belong to it.
The cork oak seems to thrive best in the south-western corner of Britain, and almost all the large specimens are to be found there: Mamhead, Devon, pl. 1765, 45 × 15 ft at 1 ft (1963); Haldon Grange, Devon, 60 × 103⁄4 ft (1967); Powder-ham Castle, Devon, 46 × 14 ft at 4 ft, and two others of somewhat smaller girth (1970); Poltimore, Devon, 45 × 131⁄2 ft at 3 ft (1964); Sharpham, Totnes, Devon, 56 × 141⁄2 ft at 4 ft (1965); Sidbury Manor, Devon, pl. c. 1830, 55 × 101⁄2 ft (1959); Tregrehan, Cornwall, 70 × 91⁄4 ft at 4 ft (1957) and 60 × 101⁄4 ft (1965); Anthony House, Cornwall, 60 × 143⁄4 ft (1971); Ince Castle, Cornwall, 50 ft high, on three stems, the largest 11 ft in girth (1969); Sherborne Castle, Dorset, 67 × 103⁄4 ft (1963); Linton Park, Maidstone, Kent, pl. 1778, 49 × 101⁄4 ft(197o); Puttenham, Surrey, 49 × 103⁄4 ft at 31⁄2 ft (1966); Osborne House, Isle of Wight, 50 × 101⁄4 ft (1972).