Aussie Gardening

[pmerretz]

Hi all,
We recently purchased a house in Toowoomba and have noticed that the tree pictured in the link has been popping up all over the place. My neighbour tells me he used to have some around 6-8 metres high all across his back fence. They are very fast growing and deciduous in winter months.
Would greatly appreciate any help in identifying this tree.
Thanks, Pete
http://home.exetel.com.au/petermerretz/pics/tree.jpg
http://home.exetel.com.au/petermerretz/pics/leaf.jpg