Quercus petraea

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Two kinds of oak are native to Britain, but they may hybridise and many intermediate forms occur. The typical Sessile oak is distinguished by the fact that its female flowers, and the resulting acorns, are stalkless. and sit directly on the twigs. Its leaves, however. are distincdy stalked (Figures 78 and 79}.

In contrast, the Pedunculate oak, Quercus robur, bears its female flowers and acorns, singly or in groups, on definite stalks or peduncles. Its leaves, as shown in Figures 31 and 82, are stalk-less or nearly so.

Another fairly constant point of distinction is the acorn shape. Sessile oak has short acorns, blundy conical in outline, that taper steadily from base to tip. The acorns of Pedunculate oak become stouter for about two thirds of their length, before they taper sharply to a blunt point and they are distinctly longer.

Tree form varies gready, but it is generally held by foresters that the Sessile oak has the better trunk of the two, more likely to persist high into the crown and yield good lengths of timber. Timber

Quercus Petraea Bud

figure 77

Winter twig of Sessile oak (life size), and two buds (X4). The clustering of the buds at the top of the twig is typical of the oak, or Quercus. genus.

figure 77

Winter twig of Sessile oak (life size), and two buds (X4). The clustering of the buds at the top of the twig is typical of the oak, or Quercus. genus.

merchants, however, find no differences between the woods of the two sorts of tree, and laboratory tests have confirmed their similarity. Both are marketed as 'English oak,'

Sessile oak is often said to be more typical of the lighter soils in the north and west of the British Isles, whereas Pedunculate oak takes the lead on the heavier clay soils farther south and east But owing to the widespread planting of both kinds, in woods in nearly every district, it is no longer possible to find clear-cut zones occupied by each sort. See page 72 for record sizes.

Oak Buds Robur

Sessile oak springs up readily from chance-sown seeds, carried by birds or beasts. Most years are irregular, but at one time acorns were so important to rural economy that woods were measured in terms of the number of swine that their oaks would support A typical entry in the Domesday Book, compiled on the orders of William the Conqueror about a.d.1086 says of a certain village: 'There is wood for forty swine,' and the village was taxed accordingly.

As more and more woods were cleared for farming, oak timber increased in value, for it had exceptional utility in country life. The heartwood of English oak has a warm, rich, deep brown colour and is naturally durable; there is a paler-coloured band of sap-wood around this, which has little durability, but this is quite thin and could easily be allowed for when the timber was worked up. Oak is strong and so hard that it presents problems in shaping and nailing - ordinary wire nails, for example, cannot be driven into it, but it can readily be secured with screws or pegs. The wide, easily-seen rays that run from the centre of the log to its circumference give it an attractive figure, which may be revealed by skilful cleaving or sawing as 'silver grain.' These rays also make it easy for a craftsman to cleave logs into segments with axe or wedge, and oak can be readily hewn with an adze to squared outlines.

Before power saws and sawmills were developed, country carpenters shaped building timbers with simple hand tools - axe, saw. wedge, and adze. All the half-timbered buildings that have survived the centuries were wrought in this way, and their timber is nearly always oak Sailing ships of all kinds, from small fishing vessels to mighty men-of-war like Nelson's Victory, were built of oak heartwood. shaped by hand into a cunning pattern of ribs, crooks and knees. Oak especially if cleft, makes an excellent fencing timber; it will serve well for both upright posts and horizontal rails. Other specialised uses are as wheel spokes, ladder rungs, and barrel staves. Much was used, as it still is today, for furniture of all kinds.

Oak branchwood is a good fuel, and it can also be made into first-rate charcoal. Even the bark is valuable, for it is rich in tannin; before imported bark and wood extracts, or tanning chemicals, were invented, it was the mainstay of the leather tanning industry.

After the virgin forests had been cleared, oaks were cultivated in various ways to meet these needs. Some were grown as coppice, cut over every 20 years or so to yield firewood or charcoal wood, fence posts, or mine props, along with regular harvest of figure 7b

Flowering rwig of Sessile oak (life size).

Lower left: Single male flower, consisting of a cluster of bracts and stamens(XlO).

Lower right: Two female flowers, consisting of bracts and four-styled pistils, which arise direcdy from a twig (X10).

valuable tanbark. This is no longer profitable, but many coppiced woods remain in western valleys, and are often mistaken for untouched natural woodland. Other oaks were grown to larger sizes, over a lifetime of 100 years or even more, to give big building timber. On many estates, they were spaced wide apart, as 'standard' trees amid coppices of hazel or other small shrubs; this arrangement gave short-boled timber, but a large proportion of stout curved branchwood suitable foi ship building. Today, however. the only real demand is for stout, straight logs that will yield long, thick planks at the sawmill. To secure these, oaks must be grown more closely together in plantations, and thinned out at intervals to encourage steady growth without undue branching.

FIGURE 79

Fruiting twig of Sessile oak with short conical acorns, tapering steadily towards the tip. sitting directly on the twigs (X;). Note the distinct leaf stalks.

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