Grevillea robusta (Bekele-Tesemma, 2007)
| Grevillea robusta (Bekele-Tesemma, 2007) |
Grevillea robusta Proteaceae Eastern Australia
Common names
- English: Silky oak, Grevillea
- Amargna: Grevila
Ecology
A very successful Australian tree planted and widely used in Africa, 0–3,000 m. Grows on fairly well drained and neutral to acidic soils but does not tolerate water logging or heavy clays. In Ethiopia, it does well in Dry, Moist and Wet Weyna Dega and Dega agroclimatic zones, 1,500–2,700 m.
Uses
Firewood, charcoal, timber (furniture), poles, fodder (leaves), bee forage, shade, ornamental, soil conservation, windbreak.
Description
A semi‑deciduous tree to 20 m or more with a straight trunk and angular branches. An oval leafy crown.
- BARK: Dark grey, rough, vertically grooved.
- LEAVES: Compound, fern‑like, very divided, leathery pale green above, silver‑grey below.
- FLOWERS: Very many, in one‑sided golden‑orange spikes, much nectar which attracts bees and sunbirds.
- FRUIT: Dark brown capsule, about 1 cm, with a slender beak, splitting to set free 2 winged seeds.
Propagation
Wildings, seedlings.
Seed
The species is a prolific seeder. Collection of large amounts of seed is time consuming. Each capsule contains only two seeds that are dispersed by wind soon after the capsule splits open. Capsules can be collected when they are brown and mature but just before they split and then be kept for drying, splitting and extraction of seeds. Germination rate 30–90 %. 70,000– 110,000 seed per kg.
- Treatment: Not necessary for fresh seed.
- Storage: Seed can be stored for up to three months, but this period can be extended if it is refrigerated. It is better to avoid storage.
Management
Moderate to fast growing. Pollarding, lopping, coppicing and pruning. Only young trees coppice well.
Remarks
It can be an important dry-season fodder although not top-quality. The leaf litter can be used as bedding material in livestock zero-grazing units. A mixture of manure and Grevillea leaves make a very good addition to the soil. The tree grows well with food crops if managed to reduce shade. The timber is hard and has an attractive grain — the red-brown colour and silky surface like that of the true oak, Quercus.
