They are also classed as a noxious weed as they spread by see and Rhizomes and when they are planted in uncontrolled areas they go rampant

They are still used in SA in gardens, but they are private or formal style gardens/reserves, where they can be kept under control, the issues occurs when they get into our waterways and bushlands, we lose control.

I can give you some alternative plants if you know what sort of soil you have and whether it is full or partial sun