Foraging for Ash Keys (Fraxinus excelsior) Oleaceae family

Learn how to identify the ash tree, then discover its food, medicine, and other uses.

As a staple tree of the British countryside, you are always near them, yet not many people know how to identify the ash, let alone know they can go foraging for ash keys.

Ash is a tall and graceful looking tree, with its branch tips curving upwards. Its form makes quite a distinctive silhouette in winter. When fully grown, ash can reach 35 metres high.

What’s in a name?

The first part of the scientific name Fraxinus is a modern adaptation of a very old word. The name for this tree seemingly has its roots in an ancient proto-european word ‘Bhrhg-s-inos’.

This is similar to the proto-european word for birch – ‘Bhrhgos’. Interestingly the Sanskrit namd for birch – ‘Bhurja’, has the same linguistic roots.

Our common name Ash has an interesting conundrum within it. How come it has the same spelling as our word for burnt residues?

Our English name for the tree comes directly from the old English word ‘æsc’. The old Norse word for the tree was ‘askr’. Both have their roots in the proto-european word ‘os’.

Our noun for fire ash, according to etymologists, has its roots from an old proto-european word ‘as’, meaning ‘to burn and glow’. The old English is æsce.  Modern spanish retains a borrowed word from Germanic languages – ascua, meaning ‘red hot coals’.

Ash is a fantastic wood for woodburners, heralded in old poems ‘that even when green it’s fit for a queen!’ I wonder if maybe the two nouns developed as they did, with such similarity, because of the excellent fires that ash makes? I would wager that our collective pyrotechnic understanding of ash, and the sharing of its knowledge, is far older than languages spoken 5-10,000 years ago.

Botanical description

To assist botanical newbies we have a glossary here, should any words befuddle you! All beginner foragers can get extra help from this guide to starting out foraging.

Antique botanical illustration of the Ash.

Leaves: Ash has large pinnate leaves. They are initially folded before rapidly expanding to full length. The leaves are sometimes copper-tinged as they first open. On a flowering tree the foliage appears after the tree has flowered.

Leaves are folded when first appearing.

When fully grown, the light-mid green leaves are approximately 25 cm long, with around 4 – 6 pairs of oblong leaflets, 6 – 9  x  2 – 3 cm. They have a single terminal leaflet.

Ash leaves appear in small groups.They can initially be copper-coloured as well.

Close inspection reveals the leaf margins are serrate, typically with 16 – 30 teeth.

Ash is the last of our native trees to come into leaf.

In the autumn, ash leaves turn a glorious yellow before shedding. Where you see them brown and shrivelled, this will be as a result of dieback. This devastating disease is discussed briefly at the end of this article.


Petioles: These tend to be swollen at the base. Typically around 10 cm long.


Roots: Large, branched and spreading ‘plate’ roots.


Twigs:  Olive-green when very young, developing into grey. The twigs have a few scattered whiteish lenticels and are flattened below the nodes. Ash twigs do not have an interpetiolar ridge.

Ash twigs are an almost olive green when young, and somewhat flattened at the nodes
Ash twigs are an almost olive green when young, and flattened below the nodes.


Buds: Charcoal black buds with three pairs of bud scales. The buds are velvety to the touch.

Ash buds are charcoal black and a little velvety to the touch.


Bark: Smooth at first, and for many years. Grey-brown and often with white patches.

Ash tree bark is smooth when young, often with white patches.

When mature, the brown-coloured bark develops narrow fissures.

Ash develops brown bark with narrow fissures on mature plants.

On old trees, you can also find mosses, lichens and moulds. Together they can make the tree quite colourful.

Older ash trees are often coated with moss and lichen.


Flowers: Ash has sprays of purple-coloured flowers without petals. The female flowers sit on yellow-green stalks.

Ash with male and female flowers.

Within a given population, ash trees can either produce male flowers only, or female only flowers, or can be hermaphrodite, producing male and female flowers on the same tree.


Flowering season: In most parts of the country, ash comes into flower from April into May. But we always need to remember the golden rules about altitude and latitude. These are that the seasons start earlier in the south and nearer sea level. Mind also that large urban areas are warmer than the surrounding countryside. So, our warmer southern areas will see flowers begin to appear earlier than elsewhere, often in late March.

Ash tree flowering in the evening light.
Ash tree flowering in the evening light.


Fruits: A winged fruit, botanically known as a samara, but commonly called keys.


Habitats: This is such a weedy tree that you can find it pretty much everywhere in the UK below 600 metres. This geographic distribution map confirms its almost omnipresence.


Parts used: Immature green fruits.


Harvesting: These seeds are designed to last 100 years. They quickly develop lignin and harden.

Ash keys turn brown and woody by autumn and can survive many decades.

So take the immature keys while you can still bite through them without fibrousness. The small round seed at the base soon grows, and if it is present beyond its initial stages, the fruits will be tough and of no use.

Ash trees don’t generally flower and fruit every year, but dieback may make them flower more.

Because eyeing up the age of the keys on the hoof is tricky, when I’m foraging ash keys I tend to keep an eye on certain plants from the early stages of flowering. Then I regularly monitor, and harvest as soon as I see them reaching full length (approximately 3 cm). Learning when to harvest these fruits is experiential, as are many other day-to-day harvesting techniques.


Edible uses: The fruits have been eaten for many centuries here in the UK. The gardener and diarist John Evelyn, produced a recipe for ash key pickle in the 17th century. This is what I base my pickle recipe on. It’s a simple method and was posted recently in my foraging guide to May.


Medicinal uses: Unlike its relative, the olive, our tree doesn’t appear to have much modern documented use as a medicine in Western traditions. Our ancestors used it to treat numerous maladies including leprosy and snake bites.


Other notes: Ash is a valued timber for wood turning, as well as for making long-lasting handles for many different tools and implements, such as axes, mattocks and various gardening tools.

The ash tree has many legends and myths associated with it. Most famously perhaps is the associations with Norse creation stories and mythology, where the ash is ‘Yggdrasil’, the tree of life.

In ancient Norse creationism, this tree is depicted at the centre of the cosmos linking nine worlds. According to legend, the tree connects all things, beings, and gods. As such it represents the great cycles of birth, growth, death and rebirth. Odin is said to have sacrificed himself on it and was hung up on it for 9 days.

Many of our ancestors beleived that if the ash trees died, this would signify the end of the world. If you have heard of ash dieback, then like me, you may think it was inevitable that it would occur. Ash dieback is caused by a microscopic fungi Hymenoscyphus fraxineus. The fungi quickly kills leaves stems and eventually the crown. Look out in the summer in July and August and see the devastation.

I am hoping through my foraging for ash keys that I can find resistant ash specimens. From knowledge about this disease on mainland Europe, scientists sadly predict that about 10 %  of our ash trees will be naturally midly resistant but just 1-2 % will show strong resistance. It is these specimens that we need to find, and then propagate their seed.

Maybe you can help and keep an eye out for any perfectly healthy ash specimens…

So go out foraging for ash keys now and let me know what you think. Remember if you have any questions on our medicinal and edible wild plants, don’t hesitate to contact me. I will do my best to help.

Happy foraging!



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