T. These well-known deciduous and evergreen trees do best on deep, moisture-retaining, rich soils, thegoing down to about 5 ft. Oaks are exceptionally long-lived, sometimes to over 1,000 years. The height is usually 60 to 80 ft. with a corresponding spread. In forests oaks which have been drawn up in an effort to reach the light are even higher. The timber is very durable and was at one time extensively used for shipbuilding. It is still employed for panelling and furniture, but is not usually fit to use until the tree is at least 150 years old. The fruits or acorns are only produced when the tree is about 70 years of age. Approximately 500 different insect species are known to attack the oak and it is often largely defoliated as the result of caterpillar infestations. A second crop of invariably appears. may also develop in late summer.
Oaks are increased from. The acorns lose their viability (power to germinate) very quickly if allowed to become dry but may be kept moist if stored on the floor of a damp outhouse or cellar. They can be sown in either autumn or spring, in in a cold frame. Protection from mice etc. can be effected by rolling the acorns in red lead prior to . If sown in the open protect also from birds by netting or proprietary bird scarers.
The two species native to Britain (both deciduous) are Quercus pedun-culata (robur) and Q,- sessiliflora (petraea). The former is the more widely distributed, especially in the south of England, and is identified by the almost stalkless leaves and the long-stalked acorns. Q. sessiliflora, also known as the durmast oak, common in the West Country, also in the north and Scotland, is rather more hardy and usually drought-resistant. It has shorter acorn-stalks and the undersides of the foliage are downy. Quercus ilex is the common evergreen or holm oak. The bark is relatively thin and black. It does well near the sea but should not be planted in very cold districts. It makes a fine hedge and may be cut back as necessary in early autumn. Q,- rubra (borealis) often called the red oak, has ample, dark green foliage which usually colours well in autumn. It is happy in industrial areas. Q,. suber furnishes the cork of commerce.