Image shows a Silk Oak tree or Grevillea robusta. Commonly known as the southern silky oak, silk oak or silky oak, or Australian silver oak, is the largest species in the genus Grevillea. It is a fast-growing evergreen tree, between 59–115 ft tall. Its spring growth flowers are golden-orange bottlebrush-like blooms between 3–6 inches long on a long stem and are used for honey production. It is a native of eastern coastal Australia. It is not closely related to the true oaks, Quercus.