Yes, they are–unfortunately. It’s a curious fact that most weeds have spread widely because they’ve been planted for their ornamental appeal. It’s only when they get out of control that they start to lose some of their appeal.
The picture above is Acacia decurrens (Early Black, or Sydney Green Wattle). It’s a native of eastern NSW, but has been widely planted around the country and has definite invasive tendencies when outside its natural ecological range. Ern Perkins’ Castlemaine Flora describes it as a ‘bushland weed’, and it has become ‘naturalised’ in almost every state, as well as in many other countries.
An additional problem with Early Blacks is that they’ve been planted by mistake in some revegetation programs: many people–and, apparently, many nurseries–don’t see the difference between Early Black and Late Black Wattles. This latter is a native to our region. The two wattles are superficially similar, but it’s easy to tell them apart, if you look carefully. All you need is FOBIF’s guide to Wattles of the Mount Alexander region!