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ash
Значение термина ash в knolik
ash - Ash
ash - G. Esche; F. Frêne; W. Onnen; E. Fuinnseog, Nuin; A.-S. Aesc.
The ash forms an erect tree with a rather rigid branch system, and is readily identified in winter by its hard black buds, borne in opposite pairs on bracket-like swellings of the smooth grey-green twigs. The terminal bud is solitary, but if it should be damaged, the stem tends to fork, as both buds of the pair beneath it grow evenly at first. Usually, one or the other assumes leadership in time, but forked stems are a common fault in cultivated ash trees. The bark of young stems is smooth and grey, becoming rougher on old trunks. The leaves do not appear until May, later than those of any other British tree, and are pinnately compound, having a number of paired leaflets on either side of the mid-rib, and ending in a terminal leaflet; the individual leaflets are lance-shaped, with a slightly serrated edge. They fall early, in October, and though they may assume bright golden tints, they more usually wither to a dull greyish brown.
The flowers appear before the leaves, in April, in loose clusters near the tips of the twigs. They are green in colour, small and inconspicuous, possessing neither calyx nor corolla, and may be hermaphrodite or unisexual; variations occur on the same tree from branch to branch or year to year.
The hermaphrodite flowers have two carpels and two stamens; in unisexual flowers either one or the other pairs of organs is lacking, according to sex. Pollination is by wind. The female and hermaphrodite flowers each produce a single seed with a long wing attached at one end. These seeds, known as " keys persist on the tree in cluster after leaf-fall, being brought to the ground by winter gales. Each seed is about half an inch long, with a wing an inch long, both being greyish brown when ripe. The seed crop varies with the season, and is very scarce in some years.
The seed is irregular in germination, sometimes growing at once, but normally lying dormant in the soil for at least 18 months after falling. After the long strap-shaped epigeal cotyledons have appeared, the first pair of leaves are simple, the second have only 3 leaflets, and these are succeeded by the normal compound leaves of the adult type.
Native in Britain, the ash is found throughout Central Europe, showing a preference for calcareous soils. Allied species occur in North America and East Asia, and are cultivated in Europe. The Manna Ash (Fraxinus ornus, L.) of southern Europe, is sometimes grown here as an ornamental tree. Its flowers bear petals, and in summer a form of sugar may be obtained by making incisions in the bark; this is known as " Manna and can be used as a sweetening.
The seed of ash may be gathered from the tree in a green state and sown at once; but is normally collected in the brown ripened stage, stored with sand in pits for 18 months, and then sown in drills in the spring. 6,000 seeds go to the pound. Seedlings are usually vigorous, and after 2 years should be transplanted for a further year of nursery growth. Stout plants about 18 inches high are best for planting out in the forest.
Ash is seldom planted pure, a nurse species such as larch being usually employed. It is generally reserved for the best soils, in particular those overlying chalk or limestone. This is advisable in view of its short growing season, together with the feet that quick- grown ash timber is the toughest and most valuable. It is very light-demanding and cannot stand overhead shade of any kind; and it is highly susceptible to damage by rabbits and grazing animals.
Open grown trees are windfirm, and the leaves shoot so late that frost damage is rare. Ash grows surprisingly well in smoky cities, where a Weeping form (propagated by grafting) is often planted.
Ash coppices freely if felled before maturity, and the quick-grown poles are valued for such purposes as tool handles. Maturing at about 120 years, when a height of 100 feet may have been attained, the timber is available in large dimensions. It is light brown in colour with little difference between sapwood and heartwood; the heart is occasionally dark brown or " black-hearted but even so, it may still be sound. Ash wood is too perishable for any use which brings it in contact with the ground. It is a first-class firewood.
The chief qualities of ash in all sizes are toughness and pliability, which taken together make it the best wood in the world for tool handles, sports goods such as hockey sticks, oars, and the framing of large vehicles, such as motor-buses. Wherever a timber is required to take a shock or a strain and absorb it smoothly without risk of fracture, ash is chosen.
Ash frequently occurs as standards in the coppice with standards woods of southern England, chiefly on the chalk. On the limestones of the north and west, pure high forest of ash may be found, but owing to the value of the timber many fine stands have been felled in recent years. As this value is based on the intrinsic merit of the home-grown wood, ash should be regarded as the best tree to plant on soils rich enough to maintain it. Although fair-sized ash trees commonly occur, very large girths are rare, and twelve feet may be regarded as the maximum.
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