By Emma Rooksby, co-ordinator of the Growing Illawarra Natives website

I've been spending a lot of time with the local Eucalypts lately, and it's always rewarding.

They are absolutely outstanding habitat trees: think koalas, possums and gliders, and of course the outstanding winged pollinators, the amazing flying foxes.

You don't always know what you're looking at, of course, as Eucalypts can be tricky to tell apart. The tree I want to focus on this week is one of the trickiest, though I'm sure you've seen many and wondered what they are.

The 'Wollongong Woollybutt' is the most widespread Eucalypt of the whole Illawarra region and can be found right along the coastal plain and throughout the escarpment from north to south. It has rough lower bark, smooth upper bark in blues and whites and greys and pretty creamy flowers in autumn. 

The weird thing about this plant is that it isn't actually its own species! It's a hybrid of two quite different species, and individual plants can vary widely in appearance. Here's a fairly 'typical' tree in the Fairy Meadow area. 

This tree is truly characteristic of the area, and is actively evolving as we speak, so in a few hundred or thousand or ten-thousand years it may have gone off in who knows what direction. 

There's almost certainly one near you, in a park or reserve or even in your garden, whether you're on the coastal plain or the escarpment, or even up on the plateau.  

One advantage of the Wollongong Woollybutt over some other local Eucs from a gardening perspective is that it doesn't tend to become absolutely massive. And it is not known for dropping limbs (though I'm not aware of any scientific studies on the topic).

That said, it is still a fairly large tree and requires a fair bit of space to grow. And if you plant one, you'll have the fun of finding out whether it tends more towards the Sydney Blue Gum (tall straight) end of the spectrum, or the Bangalay (shorter and twisted) end. Lucky dip!

While it's hard to 'get into' Eucalypts, it's super worthwhile. They absolutely dominate the Australian continent, including this region and are essential elements of our local ecosystems, supporting the precious fauna we love so much.

Next time you walk past a Eucalypt (this one or another), check it out to see how many hollows it provides for nesting birds like rosellas or king parrots, or for possums or gliders. A single old Euc can provide homes for dozens of birds and mammals.