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Kingdom Plantae Phylum Anthophyta Class Magnoliopsida Order Scrophulariales Family Oleaceae Genus Fraxinus
This genus in the olive family contain 65 species of deciduous, with a few evergreen, trees, found in woodland, mainly in temperate Europe, Asia and North America.
Fraxinus is the classical Latin name for an ash tree and excelsior means taller, indicating that this species is one of the tallest ashes. The European Ash (Fraxinus excelsior) is one of our tallest native trees, up to 40 m with a girth of up to 6m, although under extreme conditions may remain a shrub. Ashes grow at an extremely fast rate until 50 years of age; after this point they cease to increase in height. They first begin to produce flowers and seeds after they reach 30 years of age. It has a fairly open crown, becoming oval or spherical in shape as it ages. The ash develops its impressive crown when it grows in damp soil rich in minerals. It occurs commonly in the chalk and limestone regions of England, including Somerset, Derbyshire and the northern Pennines, Wales and Ireland where small pure ash woods can form. In woodland Fraxinus tends to occur in stands rather than as single trees although isolated individuals occur after colonisation of open habitats. Ashwoods are particularly characteristic of the South Downs of southern England. Main habitats include riverbanks, meadow and valley woodlands, and deciduous woodlands. It forms an important association with Quercus and also a successional stage leading to Fagus woodland. It is found amongst other pioneering species as part of the process by which woodland takes over grassland, scrubland and other open habitats. Fraxinus requires the soil to be rich in humus and nutrients, and can multiply in rich soil which accumulates in cracks of mountain limestones, forming pure ashwoods. Fraxinus is more
Scandinavian mythology holds that the ash was the 'tree of life'; it was believed to have healing powers in Britain, and was widely regarded as a source of magic and mystery. Unfortunately, the mysterious aura of the ash has declined in modern times; it is now commonly viewed as a 'weed tree' due to its rapid colonisation of new areas and fast growth.
Trunk is long and clean leading to a particularly open crown. The bark is greyish in colour and smooth, becoming fissured as it grows old. The colour of the bark is thought to give the tree it’s name. Younger branches are smooth and are light grey/olive in colour; with age these become characteristically more rugged with close, deep furrows. This tree is easy to identify in winter and is readily distinguished from other species of ash in that it has black buds, which occur in pairs, unlike the brown buds of most other ashes. The twigs are thick and flatten at leaf joints where black buds are situated opposite each other and at 90° to the next pair.
The tiny purple flowers open, in April and May before the leaves and occur in male and female clusters or racemes, the female flowers being somewhat longer than the male flowers; they are dark purple, and without petals or sepals. Both male and female flowers can occur on the same tree, but it is common to find all male and all female trees. The male flowers do not release pollen until after the styles of the female flowers belonging to the same tree have ceased to be receptive; this helps to avoid self-fertilisation. Fraxinus pollen grains have thin, beady walls and are round or oblate. They have three short, kinky furrows without pores and a surface with a reticulate, mesh network pattern which does not taper towards the furrow. Andrew (1984) describes it as a small neat grain.
Surprisingly, a tree that is all male one year can produce female flowers the next, and similarly a female tree can become male. The female flowers develop into fruits, and because they hang in bunches the fruits of the ash tree are known as 'ash keys'. The elongate, winged fruits which aid easy seed dispersal, hang in clusters, they are initially green in colour, but eventually become brown and remain after the leaves have fallen in autumn.
The leaves of the European Ash are often among the last to open in spring, and the first to fall in autumn if an early frost strikes. The compound leaves are pinnate with 7-13 toothed oval-shaped leaflets growing on either side of a central midrib with one terminal leaf, 20-35 cm long. The leaves are light to dark green and turn yellow in autumn.
Ash wood is valued for its fast growth, strength and elasticity. Because of its high flexibility and resilience to splitting Ash wood is the traditional material for and is still used to make hockey sticks, and oars, as well as walking sticks, Bows, tool handles, tennis rackets and snooker cues for its ability to withstand shock; it is also used as firewood because it burns well even when 'green' (freshly cut). Up until the second world war the trees were coppiced on a ten year cycle to provide a sustainable source of timber for fuel and poles for building and woodworking. Ash was coppiced, often in hedgerows, and evidence in the form of some huge boles with multiple trunks emerging at head height can still be see in parts of Britain. In Nothumberland crab and lobster pots sometimes known as 'creeves' by local people are still made from ash sticks. Because of its elasticity European Ash wood was commonly used for walking sticks. Poles were cut from a coppice and the ends heated in steam. The wood could then be bent in a curved vice to form the handle of the walking stick.
The ancient technique of coppicing extends the life of the tree; in Suffolk a coppiced ash is estimated to be at least 1,000 years old.
The Ash has high conservation value. The airy canopy and short leaf stay allow a lot of sunlight through to the woodland floor and hence a rich and varied ground flora can grow, such as wild garlic and dogs mercury . This also means plenty of food to allow a wide variety of insects and birds. In upland Ash woods the High Brown Fritillary butterfly may be seen. Birds such as Bullfinch enjoy the seeds and Woodcocks, Woodpeckers, Redstarts and the Nuthatch can find plenty of good nesting sites. In mixed Ash woodlands there may even be a dormouse.
Ashes make excellent specimen trees for large gardens. Ashes tolerate coastal salt air, exposed positions and urban pollution. Grow in fertile, moist but well-drained, neutral to alkaline soil in full sun.When the plant is dormant in late winter or early spring, remove any crossing shoots to maintain a healthy framework. Graft in spring onto seedling stock of the same species. There are a number of cultivars including;
The distinctive grains of Fraxinus excelsior have been recorded in deposits of several pre-Holocene interglacial warm stages in the British Isles. Isolated occurrences have been reported from the earlier interglacials but higher frequencies occur only from the Hoxnian interglacial (oxygen isoptope stage 7 or 9) and later. Wood macrofossils of Fraxinus have also been found from the Hoxnian. There are many pollen records from the Ipswichian (oxygen isotope stage 5) some of which are in relatively high percentages. Almost all of these Fraxinus identifications are from the warm, middle mesocratic phases of the interglacial stages, corresponding with the history of Fraxinus in the Holocene. While all Holocene records are for Fraxinus excelsior, some of the earlier records may be referable to other species. Fraxinus pollen has been reported from glacial cold stage contexts but is likely to be derived from reworking of earlier sediments. Isolated occurrences of Fraxinus excelsior pollen in the earlier phases of the Holocene indicate the presence of the tree in localised, small populations in Britain in the Boreal woodland prior to the full development of dense deciduous forest. Notably, one occurs in peat dredged from the North Sea bed on the Dogger Bank, the others are widespread in Britain. Pollen data suggest that before the rise of Alnus pollen around 7,000BP Fraxinus was a native and widespread tree but uncommon except on very favourable calcareous soils, whereas after about that time it increased in population substantially in most areas. As a low pollen producer, however, true Fraxinus population levels may always have been higher than pollen data indicate. After the Alnus rise, Fraxinus pollen frequencies are generally higher and in places considerably so. Most records are still sporadic, but on limestone soils in northern England and chalk areas of the south continuous pollen curves for Fraxinus often become well established several centuries before the Ulmus decline of c.5,000BP. In very favourable locations like southern Cumbria
|Fraxinus was able to reach up to 25% of tree pollen between 6,000 and 5,000BP, in association with other specialised trees like Taxus baccata and Tilia cordata. As a thermophilous tree Fraxinus excelsior was more suited to spreading during the warm and mild oceanic conditions of the mid-Holocene. The rate of spread seems to have been slow during the pre-Ulmus decline forest phases, with Fraxinus acting as a component of regenerating seral woodland, damp fen-edge locations or in drier fenwood successions. Fraxinus may have replaced Corylus in some situations. Fraxinus was the last of the mesocratic deciduous trees to expand in the Holocene (Birks 1986) and required specialised conditions or the opportunity presented by forest disturbance to become established. The high Fraxinus percentages at sites in pre-Holocene interglacials all coincide with higher non-tree pollen values and probably record conditions after natural disturbance. In the pre-Ulmus decline Holocene Fraxinus frequencies also expand temporarily after episodes of forest disturbance, whether these were created naturally or by the activities of Mesolithic hunter-gatherers. The more open conditions created by Neolithic and later forest clearance and regeneration provided many new opportunities for Fraxinus to colonise new ground and the real expansion of Fraxinus in the later Holocene outside its specialised centres was mainly stimulated by the human opening of the British woodland. Fraxinus percentages are often very high in association with archaeological sites of several periods as human settlement favoured its growth in scrub and hedge communities, and Fraxinus wood is often found in such archaeological contexts.|
Gender variation in ash
Faxinus as ozone detector
Feeding and other inter-species relationships associated with Fraxinus excelsior:
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