Botanical
The ash is one of the most beneficial of all trees. It is a light-bringer, letting light pass down through its bright green foliage in myriads of reflections, almost like a prism. It reaches very strongly up into the sky and also down into the earth, where its long grip reaches far out with a massive web of roots. These roots break down and ventilate the soil so that, with the of large amount of rich leaves it sheds every year, it is the most vital and important of trees in humus production.
It is also a healer. Hippocrates, a greek physician in 400 BC, set a trend we
still use today through his use of ash preparations to cure gout and rheumatism,
(though medicinal values of ash will have been known previously). And, since the
Middle Ages, herbal books describe the healing properties of bark, leaves and
seeds, which strengthen the liver and the spleen and are generally diuretic,
laxative, blood-cleansing and help to de-toxify the body. Until more modern
antiseptics were in use, the inner side of the bark was a remedy for healing
bleeding wounds, since its fresh sap is a disinfectant. Leaves, used inside
boots, refresh tired feet.
Ash has long been accepted as benevolent to newborn life. Because of its benign effect, sap of the tree was given to newly born babies in Scotland, while young twigs were put on the birth fire, 'in honour of the tree and as a prayer made for the newborn child.' (Fife 1994). Its vigourous growth was widely recognised. In Ireland, ash and hawthorn are the trees most commonly found at sacred springs, or 'clootie wells'.
Although found throughout Europe, ash prefers the conditions of moist air and soil, which makes it especially common in Britain. Fully grown at around a hundred years old, a three hundred year old tree is common, and far older trees are found. Its paired, feathered leaves are slightly serrated at the edges. It prefers well-watered places and grows alongside alder and other water-seeking trees.
Ash is often
described as having power over water and Celtic customs have invariably
incorporated ash wood in boats. During the clearances of the nineteenth century,
migrant Gaels carried pieces of ash over the Atlantic, and Tim Severin built his
hide boat, the Brendan, using the Irish lore of ash specifically 'from the north
side of the tree' (very rich in lignin) for his Atlantic crossing. In rain, or
cloud-making cermeonies in prehistoric Greece, Robert Graves describes the
meliae, or Ash-nymphs, as cloud spirits, or 'cloud-makers' and the daughters of
mighty sea gods, 'whose domain was originally the cloud sea' (Folkard 1892, 7).
The Greeks dedicated the ash to the sun and to Poseidon, the god of the sea.
Various customs
in England and on the continent were still alive in the nineteenth century,
based on the tree's ability to heal. In Sweden, the ash was one of the guardian
trees (Varträd), of the farm and the ash-woman (Askafroa) was provided with
regular offerings of milk or beer. Ash trees however, were planted well away
from houses and crops, because their vigorous root system can push out stone
walls and drain water from crops. Ash tree are male, female or hermaphrodite.
Flowering in April to May, long before the leaves unfold, ash has catkins (like
willow) but with large single blossoms. These develop into flat, winged nutlets,
often called 'keys', which usually hang in bunches throughout the winter, before
being scattered by the March winds.
Other notes: 
olive family
(oleaceae) common ash (fraxinus excelsior)
tree of lowlands
Wood: very strong, spears, bows, arrows, tool
handles, cartwheels, cricket bats, building, lumber, walking-sticks ‘ash-plants’
Bark: a poultice for adder bites
Seeds: ‘ash-keys’ are remedy for
flatulence, also used as capers
Medicinal: bark is astringent, good for fever
and ague, leaves are a laxative, has reputation for curing warts
Remedial: passing through cleft of pollarded
ash was a cure for hernia