Scientific Name: Grevillea robusta
Common Names: Silk Oak, Silkoak, Silky Oak, Silver Oak, Australian Silky-oak
Duration: Perennial, Evergreen
Growth Habit: Tree
Hawaii Native Status: Introduced. This naturalized ornamental and forestry tree is native to eastern New South Wales and Queensland, Australia.
Flower Color: Golden orange
Height: Up to 100 feet (30 m) tall, but usually less
Description: The flowers are clustered on the top side of horizontal, 5 inch (12.7 cm) long, brushlike inflorescences. The individual flowers have 0 petals, 4 sepals, and 4 orange stamens. The flowers contain abundant sweet nectar and attract nectar-feeding birds. The flowers are followed by blackish brown, hurricane symbol-shaped seed follicles containing 1 or 2 winged seeds. The leaves are olive green and mostly hairless above, brownish to silvery and silky-hairy below, fern-like, and deeply bipinnately divided into narrow, linear to lanceolate segments with curled under margins. 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.
Here in Hawaii, Silk Oak grows in dry forests and sunny open areas like pastures and rangelands from low to middle elevations. The plants produce an allelopathic substance that inhibits the growth of other plants. The trees have been used for reforestation, shade, firewood, and lumber. The attractively patterned wood is known as lacewood, and it is used for woodworking even though the sawdust is allergenic and can cause contact dermatitis in some woodworkers.
Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Family: Proteaceae – Protea family
Genus: Grevillea R. Br. ex Knight – grevillea
Species: Grevillea robusta A. Cunn. ex R. Br. – silkoak
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