Silk Oak

Scientific Name : Grevillea robusta A. Cunn. ex R. Br.
Common Name : Silk Oak
Chinese Name : 銀樺
Family : PROTEACEAE
Local distribution status : Exotic species

Anecdotes on plants

Origins Originated from Australia. Cultivated in tropical and subtropical regions, including provinces of South China.
Applications With its elegant tree form, distinctive leaf shape, fast growth rate and tolerance to wind, the species is commonly planted as street trees and landscaping species. During its flower period, the Silk Oak exhibits a contrast of orange-yellow and green, which is spectacularly eye-catching. Additionally, it is a nectar source to animals, which benefits the biodiversity of urban forest.
Grevillea relatives In Hong Kong, two species of Grevillea are commonly seen. They are the Silk Oak and Scarlet Grevillea (Grevillea banksii R. Br.), which are both native to Australia. The most distinct difference is that the flowers of the Scarlet Grevillea are light red (scarlet), while the Silk Oak blossoms in orange-yellow. The leaves of the Scarlet Grevillea are pinnatipartite with linear lobes, while the leaves of Silk Oak are bipinnatipartite with lanceolate lobes.
Toxicity The sap, sawdust, flowers and fruits of Silk Oak can lead to allergic contact dermatitis. Direct skin contact by bare hands should be avoided.

Traits for identification

Growing habit Evergreen tree.
Height To 25 m.
Stems Bark of trunk dark grey or dark brown, longitudinally and shallowly fissured. Young shoots rusty tomentose.
Leaves Bipinnatipartite. Leaf deeply divided into 7 to 15 pairs of primary lobes, which further pinnatipartite. Each lobe lanceolate in outline. Adaxially dark green, abaxially silvery-white sericeous, margin revolute.
Flowers Orange yellow and yellowish brown, the shape is distinct and funny. Tepals 4, fused into tube, upper portion ovoid, bend downward, bifid at anthesis. Stigma of style discoid. Flowers arranged on a same plane in the inflorescence, somewhat similar to a brush.
Fruits Follicles, ovoid-ellipsoid, slightly oblique. Dark brown when mature, splitting, with 1 to 2 seeds. Pericarp leathery. Persistent style curved.
Seeds Oblong, thinly winged.
Flowering period March to May in Hong Kong.
Fruiting period June to August in Hong Kong.
Overview of <em>Grevillea robusta</em> A. Cunn. ex R. Br.
Trunk of <em>Grevillea robusta</em> A. Cunn. ex R. Br.
Bark of trunk dark grey or dark brown, longitudinally and shallowly fissured.
Bipinnatipartite. Leaf deeply divided into 7 to 15 pairs of primary lobes, which further pinnatipartite. Lobes lanceolate in outline.
During its flower period, <em>Grevillea robusta</em> A. Cunn. ex R. Br. exhibits a contrast of orange yellow and green. At the same time, it provides nectars to animals. Flowers arranged on a same plane in the inflorescence, somewhat similar to a brush.
Follicles, ovoid-ellipsoid, slightly oblique, persistent style curved. Dark brown when mature, splitting.
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Remarks

Scientific name above is based on Hong Kong Herbarium website : https://www.herbarium.gov.hk/en/hk-plant-database/plant-detail/index.html?pType=species&oID=7636

Scientific names from other databases
― Plants of the World Online : Grevillea robusta A.Cunn. ex R.Br.

Reference