Plumbago zeylanica, Plumbaginaceae
on the bank of the Burke River near Boulia

It was a surprise to find this plant so far inland. And it was even more of a surprised to find the butterfly whose caterpillar feeds on these flowers at the site, this being some 450 km further inland than the butterfly's regular range.
It was actually the butterfly that led me to the plant.
These sightings along with some others of the butterfly out of known range prompted me to write a natural history note about it: https://www.nqnat.org/_files/ugd/570194_ba37706195a249f5b8f934b16e881d12.pdf