Western Australia’s tallest tree species naturally occurs only in a small, relatively wet portion of the state’s southwest.
Karri – Eucalyptus diversicolour – is one of Australia’s tall Eucalypts; collectively, they are the world’s tallest flowering plants.
Karri is not the tallest of them, but the biggest karri trees are among “our” planet’s most massive living individuals.
Counter-intuitive, but true: Europe’s tallest (reliably measured) tree is a karri, planted circa 130 years ago in Portugal.
The Karri Knight (circa 75 metres) is a little shorter than is the tallest WA-resident karri.
Virgin karri forest is extraordinarily beautiful, and can only be experienced in a small number of Western Australian places.
Warren National Park has no peer, at least among those which are readily 2WD-accessible.
In the featured (monochrome) image you can see the crowns of some massive karri trees, as reflected in the surface of the Warren River at 4.57 pm on August 18, 2025.
Also visible – and not just “as reflected” – are some of the other tree species that comprise a mature karri forest’s always-lovely understorey.
A forthcoming post (or two) in this series will show more of what we saw on that late winter afternoon.
The photos below show the shining trunks of two relatively young trees.
These photos were taken two days earlier, when we were briefly in Warren National Park, en route to the Yeagarup Dunes, and Yeagarup Beach, where the Warren River meets the Southern Ocean.
I’d guesstimate the pictured “shiny” trees’ age at circa 40 years.
At that age, a healthy karri is already impressively tall and straight.
At age 100 years it will likely have attained very nearly its full height.
However, if it survives for a further couple of centuries, that tree’s girth will continue to expand.
The much more massive “background” karri in these two photos are examples of that process.
Many of the “giants” in this forest have been “de-crowned” by one or more winter storms; most survive such events, and continue to increase their mass..until fire or water stress eventually defeat them.
A really big karri can yield 200 cubic metres – more than 7,000 cubic feet – of excellent timber.
Click here for a photo gallery of tall eucalypts.
The nearest of Australia’s other tall eucalypt forests are more than 3,000 kilometres away.
WA’s Karri forests now cover fewer than 2,000 square kilometres – an area less than half the size of Kangaroo Island.