@Tapirlord Okay, so after reading your comment I decided to look into the differences between species, which are in fact minute. The main one I could see on PlantNet, the Plants of SENSW Lucid app, and VicFlora is that M satureoides has flowers which are ONLY in clusters of 3, while M diemenica can have clusters of 3-8. Looking through my photographs, every single plant photographed has only clusters of 3. Though to be fair, PlantNet acknowledges that they're basically the same species, and are more accurately known as the "Mentha satureoides group".