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Species
Grevillea robusta A. Cunningham ex R. Br.
IUCN
NCBI
EOL Text
Cultivated in Nepal and elsewhere; native of Australia.
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| Rights holder/Author | eFloras.org Copyright © Missouri Botanical Garden |
| Source | http://www.efloras.org/florataxon.aspx?flora_id=110&taxon_id=200006437 |
Silk-oak coppices when cut. After being damaged by fire, a 5-year-old stand in Karnataka State, India, was cut. One year later, 93 percent of the stumps had coppiced. After 2 years 72 percent of the stumps still retained the coppice shoots, which by then averaged 4 m (13 ft) in height (1). As far as is known, vegetative propagation has not been practiced with the species.
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Flower
In racemes on leafless stem; yellow to orange. Flowering from November-December.
Fruit
Boat-shaped follicles, woody; seeds 2, winged. Fruiting December onwards.
Field tips
Bark grey, rough, irregular and deeply fissured.
Leaf Arrangement
Alternate-distichous
Leaf Type
2-pinnatifid
Leaf Shape
Lanceolate
Leaf Apex
Acute
Leaf Base
Cuneate
Leaf Margin
Entire
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| Rights holder/Author | Keystone Foundation, India Biodiversity Portal |
| Source | http://indiabiodiversity.org/species/show/229827 |
Germination is epigeal. Seedlings are grown in flats or containers in nurseries. Methods vary among the countries where silkoak is grown. In some countries 4- to 6-week-old wildings are lifted and potted and later replanted (2). Elsewhere plants are grown to 45-cm (18-in) heights in large baskets so that they can compete when outplanted (12). In Hawaii, seedlings in individual containers can be grown to a plantable size of 20 cm (8 in) height and 4 mm (0. 16 in) caliper in 12 to 14 weeks.
A handsomely straight evergreen tree, 10-25 m tall. Leaves 15-33 cm long; leaflets 7-19, 3-12 cm long, sessile, entire or pinnatifid, olive green above, silver grey silky hairy beneath; margin recurved. Racemes 5-15 cm long, appearing on the old wood, solitary, 2 or a few forming a panicle. Flowers solitary, in twos or threes; pedicel 1-1.5 cm long, glabrous, leaving a permanent white lenticular scar. Sepals 1.5-2 cm long, hooded, at first all fused together except on one side, later on fused in twos basally and apically, free for the greater length in the middle, these pairs in their turn free from each other or slightly fused above, orange yellow to orange or golden yellow to lemon yellow with dark red inner base. Stamens sessile; connective not produced beyond the anther cells; anthers about 1 mm long. Disc semi-annular. Gynophore about 2-3 mm long. Ovary glabrous; style lemon yellow, 1-2.5 cm long, dilated at the apex and bearing a greenish-yellow 1 mm long stigmatic cone. Follicle 2-seeded, 1.5-2. cm long, about 1 cm broad, silver grey to olive green, dehiscent. Seeds 1-1.5 cm long, 0.5-1 cm broad, broadly winged, thin, ovate, non-endospermic.
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| Rights holder/Author | eFloras.org Copyright © Missouri Botanical Garden |
| Source | http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=200006437 |
Silk-oak is a prolific seeder. Seeds are about 10 mm (0.4 in) long, flattened, and surrounded by a membranous wing. There are reported to be 64,000 to 154,000 seeds per kilogram (29,000 to 70,000/lb). Because of their relatively large wing, the lightweight seeds are widely disseminated by wind. Possibly because seedfall coincides with the onset of winter rains in dry leeward rangeland in Hawaii, regeneration is most prolific on these sites.
The seeds, if kept at 10 percent or less moisture content, can be stored for as long as 2 years at -7° to 3° C (20° to 38° F) with little loss in germinability. Germination of fresh, unstratified seeds requires about 20 days. Stratification at 3° C (38° F) for 30 days, or a 48-hour water soak, substantially increases germinative capacity of seeds that have been stored (19).
Proteaceae -- Protea family
Roger G. Skolmen
Silk-oak (Grevillea robusta), also often called silver-oak, is a medium to large tree commonly planted as an ornamental in many warm-temperate and semitropical climates. It has been established as a forest tree in some countries and shows promise as a fast-growing timber tree.
760-1500 m
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| Rights holder/Author | eFloras.org Copyright © Missouri Botanical Garden |
| Source | http://www.efloras.org/florataxon.aspx?flora_id=110&taxon_id=200006437 |
In Hawaii, silk-oak flowers from March through October, with the peak of flowering usually in June. The perfect yellowish orange, showy flowers are borne on 8- to 18-cm (3 to 7-in) long racemes that occur in panicles of one to several branches (3). Trees usually begin to flower at about 10 years. The fruit, a podlike follicle, 20 mm (0.8 in) in diameter, is slightly flattened and has a long-curved style. The hard dark-brown to black follicle splits open in late fall to release the one or two seeds it contains but remains on the tree up to 1 year after opening. Trees near San Jose in California have been observed to flower, fruit, and seed at times similar to those in Hawaii.
Large semi-deciduous tree. Leaves pinnately compound with deeply lobed leaflets, dark green above, silvery-grey below. The flowers are borne in horizontal, one-sided, brush-like inflorescences, orange-yellow.