Gold in Australian olive trees
Around old homesteads and abandoned groves grow olive trees nobody planted on purpose and nobody can name — survivors of a century of neglect. Increasingly, growers are realising these forgotten trees are not junk but treasure, and DNA testing is proving how little we really know about the olive.
The olive is one of the most genetically diverse crops on earth — estimates run to several thousand distinct cultivars, and that is only the ones we have catalogued. Every old olive-growing district hides trees that fit none of them: seedlings that sprang up by chance, varieties carried by migrants and then forgotten, chance crosses that quietly outlived the people who knew their names. For a long time these were treated as curiosities. That is changing.
Why old survivor trees are worth saving
A tree that has stood for a hundred years around a farmhouse, untended and unsprayed, has passed a brutal test. It has survived local droughts, frosts, pests and diseases with no help from anyone — which means it is, by definition, well adapted to that exact place. That hardiness is genetic gold in an era of erratic weather and spreading plant disease. Some of these forgotten trees also turn out to make excellent oil, having been selected long ago for quality and then abandoned when fashion moved on.
The trouble with naming them
Identifying an olive by eye is notoriously unreliable — leaf shape and fruit look can mislead, and the same variety carries different names in different valleys. So growers turn to DNA testing, and the results are humbling. A tree that plainly makes fine oil is analysed, matched against the reference databases, and comes back: no match. The variety is simply not in the catalogue. That happens often enough to prove the point — the olive’s family tree is far bigger and more tangled than our records admit.
Why this matters beyond the collectors
This is not just antiquarianism. A distinctive, climate-hardy heritage variety can become a genuinely commercial oil — a point of difference in a crowded market and a name a region can build on, exactly as growers have done with rediscovered old cultivars around the world. It is also a hedge for the future: the more of the olive’s genetic diversity we preserve, the more raw material breeders have when the next drought or disease demands a tougher tree. Every unnamed survivor is a small insurance policy against monoculture.
| Known cultivars | Several thousand catalogued worldwide |
|---|---|
| Heritage trees | Old survivors around homesteads and abandoned groves |
| Their value | Proven local hardiness plus, often, good oil |
| Why not identified by eye | Leaf and fruit looks mislead; names vary by region |
| The tool | DNA testing against reference databases |
| Common result | ‘No match’ — the variety is not yet catalogued |
What it means for a curious buyer
- Seek out rare heritage or single-variety oils for flavours you won’t find elsewhere.
- Old survivor trees carry proven local hardiness — valuable as the climate shifts.
- A ‘no match’ DNA result is a reminder of how much olive diversity remains uncharted.
- Preserving odd old varieties is a hedge against monoculture and disease.
Heritage olive varieties: common questions
How many olive varieties are there?
Several thousand distinct cultivars have been catalogued worldwide, and many old survivor trees match none of them, so the true number is higher.
Why are old, neglected olive trees valuable?
Having survived a century of local droughts, pests and disease untended, they are proven to be well adapted to their place — and some also make excellent oil.
Why can’t growers just identify a variety by looking?
Leaf and fruit appearance are unreliable and the same variety carries different local names, so visual identification often fails.
What does a ‘no match’ DNA result mean?
That the tree’s genetic profile is not in the reference databases — the variety simply has not been catalogued, which happens surprisingly often.
Why does olive diversity matter for the future?
A wider gene pool gives breeders more to work with when drought or disease demands hardier trees, and guards against the risks of monoculture.
There is real treasure in those scruffy old trees nobody planted on purpose. A survivor that has shrugged off a century of drought, frost and pests with zero help is telling you something a nursery catalogue can’t : it belongs exactly where it grows. Test its DNA and half the time the answer is a blank — no match, not in the book — which is a lovely reminder that the olive is far older and stranger than our tidy lists pretend. Save the odd ones. In a warming world of spreading disease, a hardy unnamed variety may be worth more than a famous one.
An evergreen olives101 explainer on heritage olive varieties, local hardiness and DNA identification.