Aren't the flower clusters pretty? They are about 25mm across and, unfortunately, are found on a plant which is a particularly invasive weed in east coastal areas of Australia (declared as a Weed of National Significance). It grows into dense impenetrable thickets of prickly shrubs up to 4 M tall. Originally from the tropical Americas, it was introduced in 1841 for its flowers, but was already becoming a pest by the 1860s. The PiP shows a thicket of this weed.