you can find many articles regarding ethnobotonical and ethnopharmacological uses of medicinal plants in "Journal of Ethnopharmacology" . they published numbers of papers deals with the tribles of particular area.
There is a lot more information about traditional food and medicinal plants in Northern and Western regions of Australia than in the South East, simply because traditional social structures, oral teaching traditions, and the life-ways that accompanied them, were all more severely disrupted, much earlier, by the arrival of European settlers in the later regions.
I would expect that some, (perhaps a lot of) traditional ethno-botanical and ethno-medical knowledge was lost after the first Europeans settled the Geelong area in the mid to late 1830's. A great many of the Wathaurong people died in a subsequent influenza epidemic during 1839. In many regions of Australia epidemics of accidentally introduced diseases, combined with forced removal of people from their land or enclosure of that land, (and/or deliberate massacres) disrupted the cultural traditions of the traditional custodians of the land. In the early twentieth century deliberate disruption of traditional social structures, forced removal of children to Mission schools, and similar Government policies added to this disruption.
It might be fruitful to contact the cultural heritage officer at the Wathaurong Aboriginal Corporation...