Digital Garden

Grevillea robusta 

Southern silky oak, Silk oak or Silky oak, Silver oak or Australian silver oak

Scientific Name- Grevillea robusta 

Common Name- southern silky oak, silk oak or silky oak, silver oak or Australian silver oak 

Family – Proteaceae 

Habit type – tree 

Leaves 

Leaves up to 35 cm long, pinnate with up to 22 alternate or subopposite pinnae, the pinnae with 1–several linear or linear-oblong acute lobes to deeply pinnatifid or pinnate with up to 16 lobes or pinnules, glabrous above, closely appressed pubescent beneath. 

Leaves alternate, fernlike, pinnately (almost bipinnately) compound, 15-30 cm long, exstipulate; 11-21 pairs side axes (pinnae), 4-9 cm long, deeply divided into narrow, long, pointed lobes 6-12 mm wide, upper surfaces shiny dark green and hairless, underneath silky with whitish or ashcoloured hairs. 

Bark 

The young branches are hairy and rusty brown in color. The trunk is tall and straight and has gray, rough, furrowed outer bark and orange-brown inner bark. 

Flower 

Flowers showy, yellowish, numerous, paired, on long slender stalks 1-2 cm, composed of 4 narrow yellow or orange sepals 12 mm long. Flower clusters 7.5-15 cm long, unbranched, arising mostly from the trunk, in a terminal or axillary simple or branched raceme, protandrous, petals 4, united into a tube that is mostly recurved under the broadened apex (limb); stamens 4, sessile in the concave limb; disk annular or semiannual, sometimes bilobed; ovary superior, 1-locular with 2 ovules, style curved and protruding from a slit in the perianth tube, the apex free from the limb, eventually straight, persistent. 

Fruit 

Fruits podlike, broad, slightly flattened (boat shaped), 2 cm long, black with long slender stalk and long, threadlike, curved style; 1 or 2 seeds, 10- 13 mm long, elliptical, brown, flattened with wing all around a coriaceous to woody follicle, usually oblique and opening along the ventral margin. 

FACTS & MEDICINAL USES 

Silky oak is cultivated in gardens, urban landscapes, and parks, especially in Australia, for its spectacular flowering, eye-catching foliage, and the shade it provides. 

Introduced decades ago in India, Sri Lanka and Kenya, it is cultivated there as a shade tree, to shade crops such as tea (Camellia sinensis) and coffee (Coffea arabica), because of its fast growth and good adaptation to tropical highland climates. It is also cultivated for fuelwood, including firewood and charcoal, protective windbreaks and honey production. 

The flowers produce reasonable quantities of nectar. It is reported as a honey tree in Australia and in countries where it's introduced, including India, Tanzania, Guatemala and the Dominican Republic. The honey is dark amber with a pronounced flavour, dense texture, and quick to granulate to a smooth grain. The nectar also helps to nourish and sustain nectar-eating birds in its native region, making it an important wildlife tree. 

Well-formed logs are sawn into planks used mostly for fine furniture, cabinets, interior flooring, interior house trim, doors, window-frames and the like. Selected logs are sliced for decorative veneer and the branch-wood, apart from fuelwood, is used in turnery.