91Èȱ¬

They were ridiculously early, for a start: we first looked at the house, and secretly scrumped a few deliciously sweet apples, in mid-August, weeks before you'd expect to be eating fresh apples. They were quite small, prettily rounded, and bright red: 'Discovery', I wondered? Maybe 'Royal Gala'?

Well: the truth is, I hadn't a clue. What I needed was an apple expert: someone like Joan Morgan, who's been identifying apples for the (over 2000 varieties and counting) for the last 20 years.

'It's practice,' she says. 'It's like identifying Persian carpets or paintings: there are a relatively small number of things to look for but it's only with experience that you know what you're looking at..'

Joan gets 500-plus samples through the post most years, all 'mystery' apples sent in to Brogdale for identification by ordinary gardeners like you and me. If she can't identify them at first, she analyses the DNA of the leaves: if that doesn't turn up a match, chances are it's a very local apple that's simply never been written down in the record books.

These super-rare apples are legendary: the , for example, growing only on a single island off the coast of north-west Wales and down to one single tree; or the , which grows only in Redditch in Worcestershire. Several projects are now under way to describe these ancient varieties before they're lost forever.

So here are Joan's six tell-tale signs to help you work out which apple it is growing in your garden:

1. season and usage: if the fruit is ripe to eat in August, it's an early variety, so my little apple tree definitely wasn't one of the late-fruiting types like Elstar or Braeburn. Cookers are usually larger and less highly-coloured; mine, small and red, was obviously a dessert apple.
2. colouring of skin: each apple has a particular colouring and texture: uniform, blushed, streaked, spotted, smooth or russet. Mine was a fairly uniform red, paling to green in places
3. the eye: the bit where the flower used to be sits in a 'basin' that can be open, orÌý closed, and some have particular markings: Worcesters, for example, have shallow basins with beaded skin.
4. the stalk: the other end is just as important: modern varieties like Golden Delicious are notable for their long, thin stalks, whereas older types have thicker, more stubby ones (like mine).
5. taste test: many apples have a very distinct flavour. Cox, Discovery and Ashmeads Kernel have very characteristic taste. My mystery apple, too, had a sugary sweetness, a little like strawberries
6. section test: cut the apple across its length, and across its width. Some are characteristically 'blocky' looked at in cross-section: a giveaway for Pink Lady or the Victorian pearmains.

And the verdict? My little apple turns out to be 'Devonshire Quarrenden', dating back to 1690 and really quite rare. I'm chuffed to bits. Now I've just got to figure out what that odd mid-green blocky one next to it might be...

'Devonshire Quarrenden'

Joan Morgan will be at the in Brighton this Sunday, so bring your mystery apples for her to identify – she needs three good apples and a few leaves.

Sally Nex is a garden writer and blogger and part of the 91Èȱ¬ Gardening team.

Read Sally Nex's Gardening Blog posts.