ash tree, Fraxinus excelsior

ash tree, Fraxinus excelsior

The leaves open quite late in Spring and are compound, made up of 3 to 7 pairs of leaflets (and one terminal leaflet) each up to 10 cm long. The leaves usually fall while still green.

ash tree, Fraxinus excelsior

Ash

Fraxinus excelsior is a large tree which is generally dioecious - with separate male and female trees. However, as explained below, things are not quite so simple!

The basic floral formula (for an hermaphroditic flower) is:

           
  K(4) C(4) A 2 G(2)

The ovary is superior. Each flower has 4  fused sepals and 4 fused petals and 2 anthers and/or two fused carpels.

Ash

The ash (esh, esk, ask, axe) prefers damp and calcareous (chalky) soils which it can colonise rapidly. It is a fast-growing tree and competes with birch in colonising gaps in the woodland canopy. Unlike the birch, however, the ash reaches large dimensions, up to about 45 m in height with a girth comparable to many oaks. The young branches of ash are supple and its wood can be used as a substitute for yew in making bows. Ash was also widely used in ancient times for spears. The buds of ash are sooty-black the male flowers form purple masses. The leaves are divided into leaflets. Ash is normally not as long-lived as oak, living for about 200 years, but occasional coppiced trees may perhaps exceed 1000 years. Ash makes good firewood, burning even when green.

In Norse philosophy the ash was a symbol of the cosmic Tree of Life, Yggdrasil. The roots of Yggdrasil reached down to the netherworld and are watered by three wells, including the Well of Urd (the spring of destiny) and the well of wisdom or knowledge. It connects the underworld to the heavens above and the realm of the light elves and supports all manner of living things in Midgard (Middle Earth) which feed upon it. Odin, god of knowledge and wisdom and 'Lord of Men', hung himself from its branches for nine days and nine nights to obtain the secret of the runes. He wounded himself was his own spear has he hung and came back to life to collect the runes which had fallen. Odin was also known as Woden and is linked to Wednesday (Woden's Day). According to Norse and certain Greek myths, the creator gods fashioned man from a piece of ash wood and woman from a piece of elm. There is some evidence, however, that rowan, the mountain ash, was originally the Tree of Life. The concept of the tree of life is an ancient concept that appears in the roots of most mythological or belief systems, perhaps stemming from a form of primitive tree worship or tree veneration.

Ash Canopy

The ash trees below are growing on chalky soil and seem to match the landscape - slowly crumbling into whitish fragments that match the ancient ruins of the abbey nearby. They seem to be crumbling to ash where they stand!

The ash is a deciduous tree growing up to 45 metres, but usually 12-18 metres in height. In very exposed places it may grow as a shrub. The bark is grey and smooth when young, but furrowed in old age. The characteristic black buds are 5-10 mm long and the characteristic compound leaves are 30 cm long and divided into 13 stalk-less leaflets, each about 7 cm long. Both leaflets and leaves are oppositely arranged. The leaflets have a central channel for water and hairs in this channel absorb water.

The purplish flowers lack petals and are arranged in panicles and open in April/May before the leaves and are wind-pollinated. The genders are complex - some individual ash trees are male, some female, but many are varying mixtures. The flowers may be hermaphrodite and consist of two anthers and one ovary; male flowers have an ovary which fails to develop and aborts and female flowers have abortive anthers. Reproduction is almost exclusively sexual and the fruit is a samara, or dry-winged fruit about 3 cm long and usually enclosing one seed. The first fruit develop in July, but the first viable fruit are produced in September and through to the following spring. The seeds overwinter for two winters on average before germinating, but may remain viable in the soil for up to 6 years. Seedlings are shade-tolerant, though may be out-competed by grass, and can tolerate shade for several years, rapidly springing up should an opening appear in the canopy. Ash is protandrous - the male parts maturing before the female parts, which favours cross-pollination. About 100 000 seeds are produced every second year.

Male flowers of Fraxinus excelsior. Note the characteristic 'velvet matt black' buds in opposite pairs (sometimes offset slightly) and the large terminal buds. The twigs are a characteristic pale grey (but can be greenish) and very rigid and straight and robust and flattened below the buds.

Ash trees prefer moist, well-drained, fertile and calcareous soils and grow well on limestone-rich and chalky soils (pH above 4.2) like the tree above. They usually form mixed woodlands in which oak or beech dominate, but are often dominant on calcareous soils. They prefer temperate climes, fairing badly in extreme winters and summers, and the roots will grow at a temperature range of 4 to 29 degrees C. Ash trees are good colonisers of calcareous grassland. Ash is a good coloniser of storm gaps and replaced many gaps left by dead elms in hedgerows.

Ash trees are monopodial (having a stem produced from a single leading axial shoot as in pine trees) though frost-damage may cause the stem to fork. Coppicing and pollarding also induce dormant epicormic buds (dormant buds beneath the bark of branches and stems) to activate, producing many leading shoots. The wood is ring-porous.

A young ash may grow 2 metres in a single season. Ash trees usually live for several hundred years and although not generally as long-lived as oak trees, an ash stool 18 feet and 6 inches in diameter in Bradfield Woods, Suffolk, is over 1000 years old.

Old Ash coppice stools are thought to live up to 1000 years. The leaves photographed above belong to this specimen which is growing in a beech-ash-hornbeam coppice wood (at least one part of which has flowers such as Herb Paris (Paris quadrifolia) and Common Twayblades (Neottia ovata) and is probably ancient). Early-purple Orchids (Orchis mascula), Common Spotted Orchid (Dactylorhiza fuchsii), occasional Pyramidal Orchids (Anacamptis pyramidalis), Bugle (Ajuga reptans), Hedge Woundwort (Stachys sylvatica) are also among the flowers found in this wood.

Let us take a closer look at the many black growths that adorn this tree.

These are sporing bodies of the fungus Daldinia concentrica, better knows as King Alfred's Cakes after the legend of King Alfred hiding whilst on the run from the Vikings and asked by an old woman to keep an eye on her cakes baking by the fire, but distracted by his problems he accidentally let the cakes burn! Initially covered by a red dust of spores, but appearing blacker once the spores have washed off, the internal structure of these sporing bodies consist of visible concentric layers (hence the Latin name). This fungus prefers to grow on Ash but can also be found on other deciduous trees. It is an ascomycete (see Fungi).


Article updated:
21/3/2014
16/4/2016
11/5/2020

Ash - Fraxinus excelsior