It's a legume. It's tropical or nearby. I'll shoot for the genus Cassia.

Knowing where it is growing would be useful. Could be a lot of things including Robinia pseudacacia. The pollarding would cause the foliage to grow larger than normal.

Keep the word pollarding in mind as you factor it in to the "I want one of those".

I live near sydney australia - central coast

Down under I'll go for a Tamarind, Tamarindus indica. Pollarding.

It could be a tipuana tree

Thanks shaxhome definately a Robinia pseudoacacia Umbraculifera

Yep I had a feeling it might not be something too 'exotic'. (Exotic for most of the posters in this forum, that is to say!) One of the interesting things about traveling in SE AU was seeing cultivars of northern hemisphere plants that are almost never seen in the northern hemisphere...my part of it, at least LOL. That's where I "discovered" Toona 'Flamingo', after all. And my AU thread mentions seeing a hybrid of 2 North American Robinias that I've never seen around here...maybe it is planted in the Midwest or something.

It is a bit of a shock to see a Black Locust that full and lush which makes it rather exotic to me. It is a very common forest tree here highly prized for fire wood, fence posts and rails. It is a sparse near skeleton tree though, often losing its leaves by mid-August from leaf miners. It would never enter my head, until now, that a Black Locust could look like that.

Black locusts are invasive here, but I'm definitely now considering pollarding my volunteer. Will pollarding destroy the beautiful and fragrant lowers?

Yes, very likely.

It should be noted that pollarding a standard species black locust is not going to produce the same results as in the OPs photo. 'Umbraculifera' has a very distinct growth habit that even without pollarding will produce a "lollipop" appearance on a relatively compact (rarely will ever exceed 20') tree. A squat but very dense canopy.

And Umbraculifera rarely produces any flowers.

Stunning plant but might look at something else because of the sucker issue.

Not all robinias sucker equally :-) I have grown or spec'd for clients the golden leaf cultivar 'Frisia', 'Umbraclifera' and 'Tortuosa' (aka Lace Lady or Twisty Babe) and none of them suckers to the degree the species tree does. And if planted in a lawn, any suckers are easily removed by mowing.

I like the robinia inermis. ill have a look into that about the suckers

I read about the cultivars after the correct ID. Who knew Black Locust was so exotic. It's a big plant world out there.

Frisia is banned in our state. having a look at other tress that are not suckers

Interesting that your state would ban a cultivar and not the species. I’ve not seen ‘Umbraculifera’, but ’Frisia’ and ’Twisty Baby’ are sometimes available, although not common. I’ve had up close and personal experience with the species, and it is a fierce competitor when establishing itself.

The species is also banned in most areas of the state...

Dept Primary Industries

It‘s a very impotant source of nectar for us beekeepers in my area. We love it when it’s blooming!

My large (taller than a 3 story house) black locust doesn't sucker, but it does self seed.

Maybe black locusts in Australia aren't hounded by the usual insect and disease predators that torment them in their native haunts. Wood borers here turn them into Swiss cheese and they end up shredded w/half their branches dead -- that on top of all the locust leaf-miner damage. Tho on occasion I see an isolated one that has a rough beauty. And like Anna above says, the honey produced from them is excellent -- very light-colored and vanilla-flavored.

It's a shame the thornless version doesn't flower!