Edmund Burke criticised social contract theory and argued that a society should be “a partnership not only between those who are living, but between those who are living, those who are dead, and those who are to be born”. I like the theory and it militates against the creation of an ‘Aboriginal Garden’ on the ‘Indian Reservation’ principle. Much better, and more Burkian, to regard the entire landscape has having an Indigenous Dimension.

Botanic ‘Gardens’ suffer from a degree of confusion as to whether their concern should be with botany, which is the ‘world outside’ or with ‘garden’, which is the world within the wall. This results in a nostalgic addiction to the picturesque aesthetic and some other historical styles (notably the gardenesque). They show little understanding of cultural landscapes (except for a passing interest in econmic botany). Kew exemplifies this characteristic and comes closer than other botanic gardens to transcending the attitude. My conclusion from this ramble is that the involvment of botanists would be necessary but that they would also need a landscape planner (who could be a landscape architect but would require the broader perspective one associates with planning). Sorry if this post is a footnote rather than a full response.

I suggest the following approach to providing Sydney with an indigenous component to the city plan:
1) use whatever information is available (geology, soils, history etc) to produce a physical geography map of ‘Sydney as it was’ before the Europeans arrived
2) supplement the physical geography map with a cultural geography map to show ‘Sydney as it was used and understood by indigenous Australians’
3) draw up a plan for conserving and re-creating aspects of the indigenous physical and cultural geography eg1 an area of habitat eg2 a cultural feature
My ‘model’ for the above suggestion is the map of the Lost Rivers of London and the proposal for a Recovery Plan. Many of the rivers cannot be fully recovered but there are ‘things which can be done’ – and I made one suggestion as a 2012 Chelsea Fringe project. See
http://www.gardenvisit.com/londongardenswalk/reclamation_londons_rivers/river_westbourne_revival
http://www.gardenvisit.com/history_theory/library_online_ebooks/architecture_city_as_landscape/planning_restoration_londons_rivers
http://www.gardenvisit.com/landscape_architecture/landscape_plans_planning/eid_environmental_impact_design/river_restoration_daylighting
http://www.gardenvisit.com/londongardenswalk/reclamation_londons_rivers

Yes, an indigenous layer on Sydney’s city plan would be great. It would be interesting to consider how this might be developed?

“The National Parks and Wildlife Act 1974 provides statutory protection for all Aboriginal relics and for all Aboriginal places, while the Heritage Act 1977 protects the State’s natural and cultural heritage, including archaeological remains. (Aboriginal sites and relics are primarily cared for under the National Parks and Wildlife Act, but if you have concerns or questions about a site in Sydney your first point of contact should be the Metropolitan Local Aboriginal Land Council or the Aboriginal Heritage Officer at the NSW Heritage Office.)”

I agree. What you describe is on a cousinage footing with gardens in othe parts of the world.
This page from the Royal Botanic Garden website seems to have been phrased with some difficulty http://www.rbgsyd.nsw.gov.au/welcome/royal_botanic_garden/gardens_and_domain/indigenous and outlines an approach to a landscape rather than an approach to gardens. It seems to me that Sydney would benefit from (1) an indigenous garden (2) an indigenous ‘layer’ on Sydney’s City Plan.

Would it be more accurate to say that indigenous Australians ‘did cultivate‘? I tend to think of the activity as ‘horticulture’ unless (1) it was in an enclosed space (2) it had aesthetic or metaphysical objectives, as well as food production. But definitions are mostly arbitrary, of course.

“Water lily seed bread was also popular in the Top End. The two species of water lily used were Nelumbo nucifera and Nymphaea macrosperma. During the early part of the dry season, water lilies were an important part of the diet, with seed pods eaten raw or ground into paste.”

There is some research into Australian native waterlilies occuring at Kew.
[ http://www.sciencewa.net.au/topics/environment-a-conservation/item/1192-water-lily-research-flourishing-in-the-kimberley ]

An understanding of indigenous climate science, in particular the peak waterlilly season of Yegge, would assist with a more refined understanding of landscape management practices.
[ http://www.environment.gov.au/parks/kakadu/nature-science/seasons.html ]