The Australian National Botanic Gardens has more than 4,300 species on about 40 hectares of a 90 hectare site at the base of Black Mountain.
Acacia (fam. Fabaceae).  There are about 1,075 native species of acacias (wattles). 
Eucalyptus (fam. Myrtaceae).  Eucalyptus forest is the most common type in Australia.  There are about 800 species of eucalyptus.
Banksia (fam. Proteaceae).  There are about 170 species of banksia. 
Grevillia (fam. Proteaceae).  There are over 300 species and close to 100 subspecies of grevillia native to Australia. 
Hakea (fam. Proteaceae), comprising about 150 species, are characterised by hard, woody fruits.
Casuarina and Allocasuarina (fam. Casuarinaceae) are important forest trees in Australia and also grow in parts of Southeast Asia and the Pacific.
Melaleuca (fam. Myrtaceae) includes tea trees and paper barks.
Many more interesting plants.

Part of the Eucalyptus Lawn.
The Fern Gully is a major feature.
Daily upkeep.
The National Seed Bank is getting a new facility.
The Ian Potter National Conservatory will eventually house tropical plants.  The winning "Hovering Cube" design was announced in 2016 (+), but the project has experienced several delays.
The visitor center has a well-stocked bookstore...
...and a gallery.
In late May and June an amazing small scale construction project could be viewed beside the trail at the entrance to the Botanic Gardens: a male bowerbird built a bower complete with dozens of pieces of blue plastic in hopes of wooing the female bower bird.
Not a contrail, but an interesting cloud formation.

See also:
Master Plan for the Austrailan National Botanic Gardens
Friends of the Australian National Botanic Gardens
Australian Native Plants Society