Black Mountain Nature Reserve is one of the largest and most prominent reserves in Canberra Nature Park. It is significant because of its geology and plant diversity. It is also a key element of the landscape and in the design for the national capital by Walter Burley Griffin and Marion Mahony Griffin.
 
Its early Silurian rocks (Black Mountain Sandstone), formed from sediments deposited 435 to 430 million years ago, are among the oldest in the ACT. The sandstone-derived soils are very rare in the Territory. The soils along with the complex habitat support hundres of species of plants and animals; somewhat different from other Canberra hills. There are more than 650 species of plants, including more than 60 orchids.
 
There are ten eucalypt species native to Black Mountain. The steep slopes of the mountain are cover in low open forest, dominated by Red Stringybark, Scribbly Gum, and Brittle Gum.
 
 Eucalypts, Wattles, native shrubs , grasses, herbs, and wildflowers thrive in the soils that are enriched by nutrients from invertebrates and fungi in the leaf litter on the forest floor. Half of the orchid species found in the ACT occur on Black Mountain, as well as some rare plants. Birds, small and large mammals and reptiles feed and breed on Black Mountain, many relying particularly on the eucalyptus trees for nest hollows and shelter. 

In gullies and on damp, south facing slopes, the variety of mosses, ferns, lichens and damp-loving plants redefine the word 'green'. The bark of the different tree species, with their textures, patterns and hues, delights artists and shows others that trunks are never paint-box brown. Up close, the beautiful colours of the wildflowers can be appreciated by walkers.  

Black Mountain may be the best known mountain in Australia because of research and studies done by CSIRO and others.