In Australia the Proteaceae family includes a large number of heath type plants which are particularly well developed in southwest Western Australia. Besides the Grevilleas the family includes the Hakeas, Banksias, Dryandras, Isopogons, Persoonias and Telopeas (Waratahs). There are also several rainforest Proteaceae species. These latter are generally considered to be more primitive than the drier habitat species which evolved from them. The Macadamia nut (Macadamia integrifolia) is one of these rainforest plants.
Grevillea is a diverse genus of some 350 species found throughout Australasia. Their habitats range from the sub-alpine heaths of the Australian Alps to the tropical rainforests of north-east Queensland and to the dry arid interior, and many occur on well drained light, frequently sandy, soils in sunny aspects. In size, they range from small prostrate shrubs such as G. alpina to medium size trees like the Silky Oak (G. robusta).
The Grevilleas are closely related to the Hakeas, but are distinguished from these and the other members of the family by having racemes of paired flowers which form thin dry fruits (follicles) which containing two winged seeds. The flowers secrete copious amounts of nectar and are pollinated by both insects and, particularly, the honey-eatering birds. The leaves vary from being small and entire, to toothed, or to large and dissected with many lobes and are frequently sharply pointed. Many of the Grevillea species readily hybridise, particularly when in close proximity in cultivation, and many of these hybrids have become popular garden cultivars. Grevillea "Robyn Gordon" is a hybrid between G. bipinnatifida and G. banksii.
The slightly acid, low nutrient sandy soils of the Grevillea Garden , which has a sunny aspect, favours the growing of the many Grevilleas and the collection contains species from the Hunter Region as well as a large selection from other areas in Australia, and includes many of the rare and endangered species.