Greenwattle

Acacia irrorata
Family: MIMOSACEAE
 
Just when we think the local wattle season is over, yet another of our many showy local species bursts into bloom. Than we notice that there are hundreds of them on our roadsides and waste bits of land, in the red soil areas around Toowoomba. They're looking lovely at present, and are part of the distinctive summer character of our own patch of the world.
Greenwattle Street, on the western side of town, was named after them.

Where a fast-growing, pretty, small tree is needed to fill a temporary space, this is one of the best. It has almost reached its full size by the age of about five years, and looks wonderful for the next five.
From there, it’s all downhill, however. The canopy thins out and the plant starts to look shabby. It can go on looking increasing scruffy for another ten or more years, but it might be less painful to get rid of it and fill the space with something else. Like all wattles, it has nitrogen-fixing root nodules, so killing it results in a burst of soil nitrogen becoming available to other plants put in immediately afterwards.
It its glory years, however, it is most attractive, with its dark green, shady canopy and its summer flowers.
It is a particularly good plant for wildlife. Birds like the dense foliage for nesting, and find plenty to eat in the unusually large variety of insects (including some lovely butterflies) that live on this tree.
It’s also a very good windbreak for its first ten years, while the foliage is still dense.
Don’t, however, be deceived into thinking that these wattles could be used as “nurse plants”,  sheltering slower-growing plants until they are established. Part of the secret of the cinnamon greenwattle's fast growth is its mat of shallow, greedy roots. Far from being a nurturing neighbour, it retards the growth of any small-rooted plant close by. Use it on its own, or as a very decorative infill between older plants, such as Eucalypts.

 For more on local wattles, search for Mimosaceae or Acacia using the white search box at top left.