October is all about autumn colour and Persian Ironwood (Parrotia persica) must be one of the best. It can provide fiery tints of gold and crimson, enhanced by the shininess of the leaves; but in another year it might be almost entirely yellow - which is still nice. Colouring might be bold one year, or more pastel shaded in another. Some leaves might be tinged purple all year - as was mine here at Hearne HQ this year.

It comes from the eastern Caucasus and Iran and is named after a German surgeon, explorer and naturalist, Friedrich Wilhelm Parrot. Parrot was the first person credited with climbing Mt Ararat in 1829 - though Noah is said to have floated to the top in more leisurely fashion aboard an ark some years previously.

Closely related to Witch Hazels and Sweetgums, they are small wide spreading trees, usually with multiple stems and reaching heights of 20-30ft. In the wild they can be thicket forming shrubs or tall and straight reaching 80ft. It is likely that cultivated forms here are descended from an introduction of a limited gene pool of smaller shrubbier types - but I am also told that propagating from side branch cuttings will also give a tendency towards smaller spreading trees.  Introduced to Kew from St Petersburg in 1841, the larger recorded trees in this country are at Syon House  (45ft) and Abbotsbury in Dorset (50 ft in 1972).

A is for apple. It must be the first fruit we can spell and I can think of no other tree that has quite the fame enjoyed by the apple. Depending on variety, the fruit is picked from late summer to late autumn, but the Egremont Russets and Spartans are now ripe for plucking here at Hearne Arboriculture HQ and so the domestic apple (Malus domestica) is the tree of the month for September. Famed for its fruit, the apple is also an outstanding ornamental tree in its own right, bearing a profusion of flowers in spring that open shades of pink and fade to white.

After we learn that A is for apple, we find apples appearing in fairy tales, myths and legend, often of a magical golden or silver variety. They are used to symbolise fertility, wealth, greed, eternal life, original sin, lust, temptation, knowledge and more.  Isaac Newton watched an apple drop; New York is the 'Big Apple'; there are Apple computers. An apple a day keeps the doctor away; there is the rotten apple in the barrel; there is the apple of thine eye and, of course, it was the temptation of an apple that caused Adam and Eve to be cast out of Eden...or was it?

Genesis tells us that a snake persuaded Eve to eat the apple. She then persuaded Adam and it all went horribly wrong from there. The same story appears in the Qu'ran and a very similar story, complete with sacred tree and devious snake, is found in the ancient Mesopotamian myth of Gilgamesh, pre-dating the bible by 1500 years. But Michelangelo's ceiling in the Sistine Chapel depicts the tree unmistakably as a Fig tree. He is likely to have taken his cue from the fact that Adam and Eve used fig leaves to cover their modesty after losing their innocence with the first bite, and not unreasonably may have thought that they will have grabbed the nearest leaf available. Apples aren't mentioned in the text - the original Hebrew used the word periy which means 'fruit from a branch'. It is quite possibly, as Peter Brown suggests in his book 'The Apple Orchard', an example of the  evolution of language. Just as trains were 'iron horses' and cars 'horseless carriages' because horses had been the most important means of transport, so apple may have been the most important word meaning 'fruit' before settling on the fruit of greater importance than the rest. In many languages the orange is a 'golden apple' as are apricots in Cyprus. In France the potato is the 'earth apple' and in ancient Rome the aubergine was the 'apple of insanity' and so on. So whatever Adam ate, it was bound to be an 'apple'.

Thanks to the vagaries of cross-pollination, genetic combinations and mutations, every tree grown from seed is a gamble. It may be sweet or sour, thick skinned or thin, pulpy or crisp. It may be vulnerable to disease or crop badly. It is only by chance that you will grow a desirable apple this way. If the variety has 'Seedling' or 'Pippin' in its name, it will have been found accidentally this way - such as Cox's Orange Pippin or Bramley's Seedling. The only way to reproduce trees with fruit you want is by cloning them - taking a cutting (the scion) and grafting it onto a rootstock. Incredibly, this technique was well known around 2500 years ago, although early practitioners believed that the cutting grew roots down through the rootstock into the soil from where it absorbed the precise nutrients required to produce a particular type of apple. The first Granny Smith was found on a compost heap in the garden of Maria Ann Sherwood in New South Wales in 1868; the first Bramley came from a seed planted by a young girl, Mary Ann Brailsford, in her garden in Nottinghamshire in 1809; Shaw's Pippin came from a Council refuse tip in Hertfordshire . Each of the many thousands of Granny Smith and Bramleys around the world (and every other named variety) is a cutting from a cutting of a cutting from who knows how many generations, tracing a direct line back to the originals.

While the scion dictates the type of fruit you get, the rootstock has a big influence on other things, such as tree size and vigour. East Malling Research Station, established in 1913, worked to catalogue all root stocks across the UK and Europe. By 1924 they had released categories M1-M24 allowing growers to predict rate of growth and tree size, leading orchard owners to move away from big trees to dwarf stocks that produced smaller trees giving ten times the yield per hectare that were easier to harvest. The dwarfing M9 rootstock, originally from France, is now used for around 95% of eating apples in the UK and 90% in the US and South Africa. East Malling's work is estimated to have contributed almost £9 billion to the global economy. The rootstocks used to have names (M9 was Paradise) but are now merely coded, which is a shame. Propagation of rootstocks is possible thanks to the ability of cut trees to re-sprout shoots that can then be separated with enough roots to develop into separate trees.

This progress is transforming orchards. Traditionally orchards resembled parkland with larger old trees on grazed or meadow land with hedgerows, providing a very rich and diverse habitat. The trend is now for smaller trees, more closely planted in tight rows.

It is not just the character of orchards that is changing, they are also disappearing. Once a quintessentially English part of the countryside, traditional orchards have disappeared at an alarming rate. Natural England published the results of a survey in 2011 which estimated 63% had disappeared since 1950. The Peoples Trust for Endangered Species now has this at 90% on their website. They are being lost to intensification of agriculture, development pressures, neglect and competition from imports.  Traditional orchard management created a rich habitat that supported many species such as the endangered noble chafer beetle and in 2007 they were designated as priority habitats in the UK Biodiversity Action Plan (BAP). Orchards are also a stronghold for mistletoe.

As orchards disappear, so do older varieties of apple. You won't find a Cornish Gilliflower, Hubbardston Nonesuch, Cat's Head or a  Hoary Morning in Tesco. Around half the eating apples sold in Britain are Gala and Braeburns, with a reviving Cox's Orange Pippin having about a 25% share of the market. The problem has been that many of the older varieties don't meet the standards demanded by the supermarkets. The supermarkets claim to give us what we want and that demand has apparently seen a decisive shift to bigger, shinier, prettier and sweeter fruit in recent decades. Many of the older varieties may not have made such good eating, but the loss of available variety is, I think, a shame. The British apple industry is said to have dipped into decline with membership of the EU and the sudden arrival of imports backed up with aggressive marketing campaigns - I remember all the French Golden Delicious adverts with the 'Le Crunch' slogan in the 70's. There has been some recovery of the industry but it has meant growing the varieties demanded and, perhaps ironically, the availabilty of seasonal EU workers. Growing and harvesting apples is labour intensive and this labour is by far the biggest cost to the orchard owners. The exception is perhaps cider orchards which are generally smaller fruit varieties with a high tannin content, larger trees, and less careful harvesting. But if the big cider producers want consistency, I imagine they will rely on certain varieties at the expense of others - it will be a sad day if the Slack Ma Girdle cider apple dies out.

After British DNA analysis confirmed Kazakhstan as the apple's origin, studies have estimated that we have lost some 80% of the original population gene pool, but also that the domestic apples in cultivation probably only contain some 20% of the available remaining gene pool. Preserving what remains is vital to developing new varieties and selecting for resistance to new diseases. The Americans are leading research into these wild orchards (the British efforts collapsed when funding was slashed) but we might see some new varieties emerging as a direct result. In addition to these studies, there has also been something of a resurgence of interest in the older varieties, with enthusiasts growing and sharing non-commercial varieties.  In 1990 Common Ground, a charity fostering links between communities and the natural world, organised 'Apple Day' at Covent Garden. Aimed at raising orchard awareness and regional distinctiveness, there are now Apple Days all around the country every October. If you can find one of the events you'll get to try local varieties, apple cake and probably some scrumpy too.

Once you are growing an apple tree, you want a good harvest of nice fruit. At least you would think so - but I've visited so many houses where I've seen a bowl of supermarket apples in the kitchen and a tree and lawn laden with apples in the garden. Nevertheless, a frequent question I am asked is about pruning apple trees since people seem to believe that they must be pruned and, indeed, an old saying is that you should thin out the branches until you can throw your hat through the crown or, in Monty Don's words, a bird can fly through. The idea behind this is that you open the crown so that light and warmth can ripen the apples while the more open airy structure will be less prone to disease. Some orchards will also pick off developing apples if there are too many, so that the tree can concentrate its resources into producing fewer but bigger and better fruit. This thinning also avoids the risk of bumper crops one year followed by trees resting and producing very little the next year.

Finally, in late summer or autumn, you can pick your apples to eat, or cook, or make cider or brandy. And perhaps an apple a day will keep the doctor away. Stem cells from a Swiss variety have been used to boost skin growth and reduce wrinkles - a capacity that is being studied by researchers working on the prevention of certain cancers and vascular diseases.