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A beekeeper's look at Eucalyptus marginata, the tree behind our darkest and slowest honey
Drive an hour east of Perth and the paddocks give way to something older. The gravel turns rusty red, the road starts climbing, and suddenly you’re under a canopy that has been standing since well before anyone thought to put a fence around it. That’s the jarrah forest, and for us it’s less a landscape than a workplace. We move hives into it, wait, and hope the trees are in the mood.
The jarrah tree is one of those species that people in WA grow up around without ever really looking at. It’s the timber in the old floorboards, the firewood in the shed, the name on half the streets in the hills. It’s also, quietly, the reason Western Australian honey has a reputation that reaches as far as Japan and the UAE.
What does a jarrah tree actually look like?
Jarrah goes by the botanical name Eucalyptus marginata, and in good country it grows tall and fairly straight, with a heavy crown that spreads once the tree has some age on it. Younger regrowth looks quite different, often scrubbier and multi-stemmed, which is why two jarrahs can look like two species if one has been cut over and the other hasn’t.
Bark. Grey brown, rough and fibrous, shedding in long vertical strips that run the length of the trunk. It holds that roughness all the way up rather than going smooth in the upper branches. Nothing about it is neat.
Leaves. This is the giveaway. Jarrah leaves are long and gently curved, roughly the length of your palm, glossy dark green on top and noticeably paler underneath. A breeze through the canopy makes the whole tree flicker between two colours. Get one in your hand and turn it over, because that two toned leaf separates jarrah from most of the eucalypts standing next to it.
Flowers. Creamy white and fluffy, made up of masses of fine stamens rather than petals, sitting in clusters through the canopy. Like all eucalypts, each bud wears a little cap that pops off as the flower opens, and the ground under a flowering jarrah ends up littered with them.
Gum nuts. Small, round and woody, sitting in tight clusters after flowering. They’re modest compared to the big urn shaped nuts you get on marri, or red gum as most people around here call it, and that size difference is one of the quickest ways to tell the two apart on the ground.
If you’re trying to identify one, start with the leaf and check whether the underside is clearly paler than the top. Then look at the bark for those long fibrous strips, and finally check the gum nuts on the ground for something small and round rather than large and urn shaped. Three checks and you’ll have it.
Underground, the tree is doing something more impressive than anything above the soil. Jarrah sends roots down through cracks in the laterite to reach water sitting well below the surface, which is how a forest survives a Perth summer on rainfall that stopped in October. That deep water is also part of why the trees can keep flowering through heat that flattens everything else.
Jarrah tree vs red gum: can you tell the difference?
Worth clearing up before anything else, because it trips almost everyone up at some point. The red gum growing through our patch of the south west is marri, Corymbia calophylla. Same tree, two names. Red gum is what people around here have always called it and it’s the name on our jar, marri is the name you’ll find on a botanical list, and anyone telling you marri honey and red gum honey are two different products is describing the same tree twice.
Elsewhere in the country red gum can mean something else again, most often the river red gum along the inland waterways, which is why it’s worth knowing which forest a red gum honey actually came out of rather than going off the name alone.
This is a red gum on the left and a jarrah on the right, growing side by side. If you didn’t know what you were looking for, it’d be pretty easy to walk straight past and assume they were the same tree.
Jarrah has rough, fibrous bark that runs vertically along the trunk, with long, slightly curved leaves that are dark green on top and noticeably paler underneath. Its flowers are creamy white, followed by relatively small, rounded gum nuts.
Red gum is the one that catches people out, because it grows through the same country and often close enough to jarrah that the branches touch. Its bark is patchier and more mottled, smoother than jarrah’s rather than fibrous all the way up, and it bleeds a dark red sap that runs down the trunk and stains it, which is where the red gum name came from in the first place. The gum nuts settle it though. Red gum drops big urn shaped nuts, the ones kids fill their pockets with, next to jarrah’s small round ones.
For us, the difference isn’t just botanical. The tree the bees are working determines the nectar coming back to the hive, and ultimately the honey that ends up in the jar. A jarrah flow produces a very different honey to a red gum flow, even when the two trees are growing within flying distance of one another. Put a jar of jarrah next to our red gum honey and you can taste which tree each one came off.
How big does a jarrah tree grow?
A mature jarrah in decent country reaches around 40 metres, with a trunk that can push past two metres across on the older ones. They’re not the tallest trees in the south west, since karri takes that title comfortably, but a big old jarrah has a heft to it that’s hard to convey until you’re standing under one.
Age is the part that catches people out. Jarrah grows slowly, and the trees still standing in old-growth pockets are commonly several hundred years old, with some estimated well past four hundred. A tree that was already mature when the Swan River Colony was founded is not unusual in the right patch of forest.
Most of what you’ll drive through in the hills today isn’t that, though. A lot of the jarrah forest has been cut over at some point in the last century and what’s grown back is younger, denser and thinner in the trunk. It looks like forest, and it is forest, but it isn’t the same thing as old growth and it doesn’t behave the same way. That’s worth knowing, because a forest that takes four hundred years to build isn’t something that comes back on a management plan timeline.
Where to find the King Jarrah
If you want to stand under one of the big old ones without going bush, there are two trees in the south west that carry the name King Jarrah, and people get them mixed up constantly.
The one in Wellington National Park sits in the Ferguson Valley near Collie, out along King Tree Road. It stands around 36 metres and is estimated at somewhere between 300 and 500 years old. There’s a boardwalk and a viewing platform now, and the path in is bitumen and mostly level, so it suits people who wouldn’t manage a bush track. Entry is free. Leave the dog at home though, because there’s 1080 baiting through that country.
The other King Jarrah is at the edge of the Manjimup townsite, with a loop trail around it, and that one is reckoned to be over 500 years old. It’s an easy stop if you’re already heading south through the timber towns.
There’s a third contender that doesn’t get the title, which is the Old Jarrah Tree standing on a street corner in Armadale. It’s been lopped over the years so it’s nowhere near full height, but the age estimates on it run from 400 all the way to 800 years, which would make it older than either of the kings.
Trees like these are worth seeing because they’re the exception rather than the rule. Most of what’s left standing is younger than it looks, and a jarrah that’s had four or five hundred years to get on with it is a different proposition entirely.
Where jarrah grows, and why it grows nowhere else
Jarrah is endemic to the south west corner of Western Australia and it doesn’t occur naturally anywhere else in the world. The belt runs from roughly the Gingin area in the north down through the Darling Range and the hills behind Perth, on through Dwellingup, Collie and Bridgetown, and out towards Manjimup and the south coast. It’s a strip a couple of hundred kilometres wide and that’s the whole of it.
If you’ve driven through the Perth Hills, Dwellingup or the forests around Collie, chances are you’ve spent plenty of time under jarrah without giving the trees much thought.
The reason it stays put comes down to dirt. Jarrah grows on lateritic gravel, an ancient ironstone soil that is poor in almost every nutrient a plant would normally want. Most trees would sulk. Jarrah has spent a very long time adapting to exactly those conditions, and it thrives on ground that would be hopeless for farming.
That’s the short version of why you can’t plant a jarrah forest in Victoria and expect the same honey. The tree might survive. The soil, the rainfall pattern and the four hundred year old root systems won’t come with it.
The flowering cycle every WA beekeeper plans around
Here’s the part that separates jarrah from a normal honey crop. Jarrah doesn’t flower every year. The trees run on roughly a two year cycle, so a jarrah that gave you a heavy flowering last season isn’t likely to do much this one.
What makes it a guessing game is that the forest doesn’t move as one. Every tree and every patch sits at a different point in its own cycle, and there’s no way to stand in a stand of jarrah and know for certain what it’ll do come summer. Some seasons it’s strong right across the range, some seasons it’s patchy, and some seasons it barely bothers. We plan around what we’re seeing in the bud rather than around a calendar.
When it does go, the canopy fills with clusters of creamy white blossom and the sound under those trees is something else. Up close each flower is a soft burst of fine stamens rather than anything with petals, and a good flowering turns whole sections of canopy pale from a distance. We’re watching bud development the summer before to work out where the hives should sit, and even then the weather can undo it. A run of hot windy days at the wrong moment can dry the nectar off before the bees get to it.
All of which is why real single origin jarrah honey is not something anyone can promise you a truckload of on demand. If a supplier always has unlimited stock at a low price, that’s worth a second thought.
Why the jarrah tree makes such an unusual honey
Nectar from the jarrah tree produces a honey that behaves differently to the mild, pale, quick setting honeys most people grew up on. It comes out a deep amber, closer to caramel or treacle in the jar, with a rich malty flavour that has a bit of bitterness sitting behind the sweetness.
It’s also naturally high in fructose and low in glucose. That higher fructose-to-glucose balance is one reason a jar of raw jarrah honey stays liquid for much longer than many other honeys, and it’s the same balance behind jarrah’s reputation as one of the lower GI honeys. Red gum sits in that conversation too, and so does blackbutt some seasons, but jarrah is the one that gets named first. We don’t have GI testing on our own batches to point you at, so we’d rather tell you that than quote a number we can’t stand behind.
Then there’s the activity, which is the part most people are really asking about. Jarrah carries a naturally high level of antibacterial activity, and in Australia that gets measured as a Total Activity rating, written as TA. Our jarrah is sold as TA35+, and TA35+ is what the label says every time, because it’s a guaranteed minimum rather than a batch by batch number. The most recent independent results from the Y-Trace lab here in WA came back at TA42, comfortably above what’s printed on the jar. A TA rating is simply a measure of that antibacterial strength, tested in a lab rather than estimated, and anything above TA35 sits at the strong end of what the WA forests produce.
The reason we test every single batch rather than rating the honey once and printing it on every label from then on is that activity moves. It shifts with the season, the patch of forest and how the honey is handled after extraction, and a number from three years ago tells you nothing about the jar in your hand. That isn’t just our opinion either. A 2023 study in the Journal of Applied Microbiology tracked jarrah and marri honeys stored at different temperatures and found the antibacterial activity dropped away with heat and time, with the hydrogen peroxide falling to negligible levels within weeks at higher temperatures. That’s the whole case for keeping honey raw and testing it batch by batch, and it’s the difference between a certified rating and a number somebody has printed on a label.
Jarrah and manuka also get their antibacterial reputation in different ways. Jarrah’s Total Activity is primarily associated with peroxide activity generated naturally within the honey, while manuka is best known for its methylglyoxal (MGO) content. They’re different systems rather than interchangeable ratings, which is why jarrah honey vs manuka honey is a longer conversation than matching the numbers on two labels. None of it tells you much about what the honey does for you day to day either, and the honest version of the jarrah honey benefits story is more modest than the internet would have you believe.
Jarrah and karri: the other tree people mix up
Karri is easier again. Karri is the tall smooth trunked one further south around Pemberton, pale grey and orange and impossible to mistake once you’ve seen it. If you’re standing under something enormous and smooth, you’re not under jarrah.
Bees don’t read labels, which is why hive placement and timing matter so much. A hive sitting in mixed forest during a red gum flow produces red gum honey, not jarrah, and the two are quite different in the jar. The same goes for every one of the types of honey we take off across a season, each one shaped by whatever happened to be flowering at the time.
The forest isn't guaranteed
Jarrah dieback is caused by Phytophthora cinnamomi, a microscopic organism that lives in the soil and behaves a bit like a water mould. It isn’t a fungus in the ordinary sense and it isn’t something you can see. It attacks the fine roots that a tree uses to take up water, and because jarrah depends so heavily on its root system to reach water deep underground, an infected tree slowly loses the ability to keep itself going.
It travels in soil and water. Mud on a boot, a tyre, a trailer or a piece of machinery is enough to carry it into clean country, and it moves downhill through wet ground once it arrives. That’s why you’ll hit wash down stations at the edge of certain areas in the south west, and why tracks get closed off through the wetter months when the risk of spreading it is highest. Those closures frustrate people, but they’re the main thing standing between infected and uninfected forest.
Once it’s in a patch of bush there’s no cure. Management is about containment rather than treatment, which puts the responsibility on everyone moving through the forest rather than on anyone coming along afterwards to fix it.
For a beekeeper this isn’t an abstract conservation issue. Fewer healthy trees means fewer flowering events, and a forest that has taken centuries to build isn’t something that can be replanted on a five year plan. We’re careful about where our gear has been for the same reason we’re careful about anything else in this job, which is that the forest is the business.
From the tree to the jar
The soil, the age of the trees, whether the forest decides to flower at all, whether our hives are sitting in the right patch of it at the right fortnight. None of that is up to us. We just try to be in the right place and then get out of the way.
By the time you twist the lid off a jar of jarrah honey, most of the important decisions were made months earlier by the forest itself.
What that season produced is sitting on our shelf now, alongside the rest of the Western Australian honey we took off this year, and it lasts as long as it lasts.
Common questions about the jarrah tree
What is the scientific name for the jarrah tree?
Eucalyptus marginata. The name marginata refers to the fine rim running around the edge of the leaf.
Is jarrah a eucalyptus tree?
Yes. Jarrah is a true eucalypt, one of hundreds of eucalyptus species across Australia, and one of the few found only in the south west of WA.
How long does a jarrah tree live?
Several hundred years in undisturbed forest, with some of the older standing trees estimated well past four hundred.
How big does a jarrah tree get?
Around 40 metres tall at maturity, with a trunk that can exceed two metres across on older trees.
What colour are jarrah tree flowers?
Creamy white, made up of fine fluffy stamens rather than petals, appearing in clusters through the canopy.
What does jarrah tree bark look like?
Grey brown, rough and fibrous, shedding in long vertical strips and staying rough right up into the branches.
Is red gum the same tree as marri?
In the south west of WA, yes. Red gum is the common name people here use for marri, Corymbia calophylla, so red gum honey and marri honey come off the same tree. Red gum can refer to different species in other parts of Australia, which is where the confusion usually starts.
How can you tell a jarrah tree from a red gum?
Look at the gum nuts first. Red gum drops large urn shaped nuts, jarrah drops small round ones. Jarrah also has fibrous bark running vertically up the trunk and long curved leaves with a paler underside, while red gum has patchier, more mottled bark and bleeds a dark red sap that stains the trunk.
How can you tell jarrah from marri?
Marri and red gum are the same tree, so it’s the same answer. Marri’s gum nuts are large and urn shaped, jarrah’s are small and round, and marri’s patchy bark and dark red sap set it apart from jarrah’s rough fibrous trunk.
Where is the King Jarrah tree?
There are two. One is in Wellington National Park in the Ferguson Valley near Collie, reached from King Tree Road, and the other is on the edge of the Manjimup townsite.
How old is the King Jarrah?
The Wellington National Park tree is estimated at 300 to 500 years old and stands around 36 metres. The Manjimup one is thought to be over 500 years old.
Where are jarrah trees found in Western Australia?
Through the south west, from around Gingin in the north down through the Darling Range, Dwellingup, Collie and Bridgetown towards Manjimup and the south coast.
Is jarrah a hardwood?
Yes, and a famously dense one, which is why it’s been used for flooring, sleepers and furniture for well over a century.
When do jarrah trees flower?
Through the warmer months, and not every year. Individual trees run on roughly a two year cycle, and because different trees and patches sit at different points in that cycle, what the range does in any given season varies a lot.
Can jarrah trees grow outside Western Australia?
They can be cultivated elsewhere, but they only occur naturally in the south west of WA, and the honey depends on the whole system rather than the tree alone.
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