Online Manual for the Forest Tree Seeds of Kerala

A Kerala Forest Department Funded Project


Dr. K Sudhakara
Professor & Head of the Department
Dept. of Silviculture & Agroforestry
College of Forestry, Kerala Agricultural University, Thrissur 680 656
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Scientific Name  Grevillea robusta A. Cunn. ex R.Br.
Vernacular name  Silver oak (Malayalam); Savakumaram (Tamil); Silver oak (Kannada) (Chacko et al., 2002).
Common name  Silver oak (Chacko et al., 2002); Silk oak (Gamble, 1922).
Synonyms 
Family  Proteaceae
Subfamily 
Origin  Native of Australia.
Distribution  Native of Australia. In Kerala, it is grown as shade tree in tea and coffee plantations. It is very popular in tropical and subtropical climate and extensively grown in gardens, parks, and on road-sides for showy appearance (Bose et al., 1998).
Description  Fast growing, medium sized evergreen tree attaining a height of 30 to 35 m and a breast height diameter of 50 to 60 cm (Luna, 1996; Chacko et al., 2002).
Flowering season  March to April.
Fruiting season  December to January; June to August (Sen Gupta, 1937; Chacko et al., 2002).
Flowers  Flowers orange coloured, solitary, borne in racemes, 10 to 15 cm long, on short branchlets; perianth lobes 4, reflexed; stamens 4, projecting beyond the perianth with the style (Bose et al., 1998).
Fruits  Follicle, oblique, oblong, compressed coriaceous, 1.5 cm long, containing one or two seed.
Fruit type  Follicle.
Seeds  Seeds one or two and papery (Luna, 1996; Chacko et al., 2002).
Seed length  1.21 cm (Chacko et al., 2002).
Seed width  0.83 cm (Chacko et al., 2002).
Seed thickness 
Seed weight  35000 seeds/kg (Kindt et al., 1997) - 95000 seeds/kg (Kumar and Bhanja, 1992; Chacko et al., 2002).
Seed dispersal  Wind dispersal.
Seed Collection  Capsules are collected from the tree when they turn brown in colour (Kumar and Bhanja, 1992). The capsules dehisce while still attached to the tree (Chacko et al., 2002).
Transportation of seeds  Capsules collected in cotton bags are transported to the processing centre as quickly as possible (Chacko et al., 2002).
Seed processing  The fruits are dried under sun to release the seeds (Kumar and Bhanja, 1992; Chacko et al., 2002).
Seed storage  Orthodox (CABI, 1998). Seeds with less than 10% moisture content can be stored for two years at -6.7oC to -3.3oC (Chacko et al.,2002).
Viability period  Short, up to two months (Kumar and Bhanja, 1992; Chacko et al.,2002).
Seed emptiness  Moderate (Chacko et al.,2002).
Seed pre treatment  Soak the seeds in hot water for 3 min (Kindt et al.,1997; Chacko et al.,2002). Soak in cold water for 12 to 24 hrs (Edwards and Naithani, 1999).
Germination type  Epigeal (Chacko et al.,2002).
Germination percentage  20 to 90 (Kumar and Bhanja, 1992; Carlowitz, 1991; Devaraj et al., 1999 Chacko et al., 2002).
Germination period  11 to 29 days (Chacko et al.,2002).
Nursery technique  Seeds are sown in nursery bed during August and the seedlings are transplanted when they are 6 to 8 cm tall into polythene bags. Seedlings are ready for outplanting in ten months (Kumar and Bhanja, 1992; Chacko et al.,2002).
Method of propagation  By seeds.
Vegetative propagation 
Pests  No information (Chacko et al.,2002).
Diseases  No information (Chacko et al.,2002).
Medicinal properties  The flowers are important source of honey and the bark yields tannin and gum.
Uses  The leaves of the tree are valued as green manure in coffee and tea plantation. The bark of the tree yields a yellow gum containing moisture, resin and CaO2. The main uses include shading over tea and coffee plantation, production of mulch and honey, beautification and wood production for fuel and poles (Nair, 1993). The heartwood is strong, durable and excellent for cabinetwork. The timber is also used in parquetry and turnery, making railroad ties, plywood panelling, air-freight cases and furniture. Hydrocyanic acid has been detected in the fruit and flowers (Wong, 1974).
Wood properties  Wood light reddish brown, sapwood greyish white. It is moderately hard and moderately heavy. Pores moderate sized. Air dry weight about 640 kg/m3.
References  Get ...
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