Common Name: Silky Oak, Southern Silky Oak and Australian Silver Oak.
Etymology: Grevillea: Named after Charles F. Greville (1749–1809), Scottish horticulturalist, robusta: Feminine of robustus (robust or strong).
Origin: Coastal gullies, forest and rainforests of NSW and Queensland, Australia.
Description: Fast growing tall single trunked tree up to 40m with a conical crown.
Foliage: Alternate, deeply bipinnatisect with approximately 20 narrow lobes, 300mm long, mid to dark green on top and silvery silky pubescent underneath.
Bark/Trunk: Rough, furrowed grey to brown bark.
Flowers: A toothbrush type flower head (one side raceme) 100mm long in clusters of 3-5 racemes, with 60-80 flowers each, the curved floral tube and styles orange/yellow. The styles are looped at first then straighten out. Main flowers mid to late spring.
Fruit: Purple to black woody follicles, 30-50mm long. They have tart, crimson, edible flesh surrounding 2 dark red flattened seeds about 20mm long, ripe in summer.
Growth Requirements: Prefers rich well drained soils in full sun or part shade position. Will tolerate both clay and sandy soils and even moderately drained soil but unpredictable in wet soils (may die or fall over). Tree is second line salt tolerant, moderate lime tolerant, drought tolerant but will need protection from frost when young.
Uses: Australian native gardens, screen tree, shade tree, street tree (pollution tolerant), wind break, bee attracting, butterfly attracting, bird attracting, erosion control and pioneer tree. It was widely used for external window joinery (as it is resistant to wood rot) before aluminium and was used in furniture, cabinetry and fencing although use of this timber now has been restricted due to population decline. It has more recently been used in guitar making due to its tonal and aesthetic qualities.
Propagation: Seed or firm tip cuttings in summer, autumn and winter.
- Australian Trees by Leonard Cronin.
- Own sources.