Fagus sylvatica, the European beech or common beech, is a deciduous tree belonging to the beech family Fagaceae. Fagus sylvatica is a large tree, capable of reaching heights of up to 50 m (160 ft) tall and 3 m (9.8 ft) trunk diameter, though more typically 25–35 m (82–115 ft) tall and up to 1.5 m (4.9 ft) trunk diameter. A 10-year-old sapling will stand about 4 m (13 ft) tall. It has a typical lifespan of 150–200 years, though sometimes up to 300 years. In cultivated forest stands trees are normally harvested at 80–120 years of age. 30 years are needed to attain full maturity (as compared to 40 for American beech). Like most trees, its form depends on the location: in forest areas, F. sylvatica grows to over 30 m (100 ft), with branches being high up on the trunk. In open locations, it will become much shorter (typically 15–24 m (50–80 ft)) and more massive. The leaves are alternate, simple, and entire or with a slightly crenate margin, 5–10 cm long and 3–7 cm broad, with 6–7 veins on each side of the leaf (7–10 veins in Fagus orientalis). When crenate, there is one point at each vein tip, never any points between the veins. The buds are long and slender, 15–30 mm (0.59–1.18 in) long and 2–3 mm (0.079–0.118 in) thick, but thicker (to 4–5 mm (0.16–0.20 in)) where the buds include flower buds. The leaves of beech are often not abscissed (dropped) in the autumn and instead remain on the tree until the spring. This process is called marcescence. This particularly occurs when trees are saplings or when plants are clipped as a hedge (making beech hedges attractive screens, even in winter), but it also often continues to occur on the lower branches when the tree is mature. Small quantities of seeds may be produced around 10 years of age, but not a heavy crop until the tree is at least 30 years old. F. sylvatica male flowers are borne in the small catkins which are a hallmark of the Fagales order (beeches, chestnuts, oaks, walnuts, hickories, birches, and hornbeams). The female flowers produce beechnuts, small triangular nuts 15–20 millimetres (0.59–0.79 in) long and 7–10 mm (0.28–0.39 in) wide at the base; there are two nuts in each cupule, maturing in the autumn 5–6 months after pollination. Flower and seed production is particularly abundant in years following a hot, sunny and dry summer, though rarely for two years in a row. The natural range extends from southern Sweden to northern Sicily, west to France, southern England, northern Portugal, central Spain, and east to northwest Turkey, where it intergrades with the oriental beech (Fagus orientalis), which replaces it further east. In the Balkans, it shows some hybridisation with oriental beech; these hybrid trees are named Fagus × taurica. In the southern part of its range around the Mediterranean, it grows only in mountain forests, at 600–1,800 m (1,969–5,906 ft) altitude. Although often regarded as native in southern England, recent evidence suggests that F. sylvatica did not arrive in England until about 4000 BC, or 2,000 years after the English Channel formed after the ice ages; it could have been an early introduction by Stone age humans, who used the nuts for food. The beech is classified as a native in the south of England and as a non-native in the north where it is often removed from 'native' woods. Localised pollen records have been recorded in the North of England from the Iron Age by Sir Harry Godwin. Changing climatic conditions may put beech populations in southern England under increased stress and while it may not be possible to maintain the current levels of beech in some sites it is thought that conditions for beech in north-west England will remain favourable or even improve. It is often planted in Britain. Similarly, the nature of Norwegian beech populations is subject to debate. If native, they would represent the northern range of the species. However, molecular genetic analyses support the hypothesis that these populations represent intentional introduction from Denmark before and during the Viking Age. However, the beech in Vestfold and at Seim north of Bergen in Norway is now spreading naturally and regarded as native. Though not demanding of its soil type, the European beech has several significant requirements: a humid atmosphere (precipitation well distributed throughout the year and frequent fogs) and well-drained soil (it cannot handle excessive stagnant water). It prefers moderately fertile ground, calcified or lightly acidic, therefore it is found more often on the side of a hill than at the bottom of a clayey basin. It tolerates rigorous winter cold, but is sensitive to spring frost. In Norway's oceanic climate planted trees grow well as far north as Trondheim. In Sweden, beech trees do not grow as far north as in Norway.