Calamus subinermis (PROSEA)
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Introduction |
Calamus subinermis H. Wendl. ex Beccari
- Protologue: Rec. Bot. Survey India 2: 212 (1902).
- Family: Palmae
- Chromosome number: 2n= unknown
Vernacular names
- Malaysia: rotan batu, rotan tunggal (Malay), mangkawayan (Kadazan/Dusun).
Origin and geographic distribution
C. subinermis is found along the coast of Sabah (Malaysia), from Labuan on the west coast to Tawau on the east coast and probably extends south along the coast of East Kalimantan in Indonesia and into Sarawak. It is also found in Palawan, the Philippines. It does not occur far inland.
Uses
C. subinermis is used mainly as a structural cane in the manufacture of furniture. Very little of it is used for handicrafts. The shoot apex is cooked as a vegetable and the fruits are sometimes eaten.
Production and international trade
C. subinermis is exported from Sabah mainly to Singapore for reexport overseas. At the peak of trading in 1987, no more than 3000 t were exported. Due to overharvesting both in Sabah and in Palawan, export has now dropped drastically.
Properties
Apart from its slightly smaller diameter, C. subinermis is similar to the high quality furniture cane C. manan Miq. in many respects. It is a hard cane suitable for nailing, with a smooth, yellowish surface and an even diameter, and is much sought after as a structural cane in furniture manufacture. There are about 4700 cleaned seeds in 1 kg.
Description
A largediameter rattan which may be solitary or clustering with stems reaching 40 m or more. Stem without leafsheaths 1830 mm in diameter, rarely to 40 mm, attaining 50 mm or more with sheaths; internodes 1530 cm. Leaf to 4 m long including cirrus; leafsheath covered with greyish indumentum, spineless to densely covered with fine horizontal black spines 15 mm long; knee prominent, unarmed; ocrea to 5 mm high; petiole to 10 cm or more in juvenile fronds; rachis to 2 m long with 25 pairs of leaflets or more; leaflets lanceolate, up to 40 cm×6.5 cm, armed with black spines on upper surface of the 5 main veins and margins, unarmed on lower surface; cirrus to 2 m. Inflorescences: the male branching to 3 orders, the female to 2 orders, to 1.5 m long with up to 10 pairs of partial inflorescences, longest to 75 cm; male rachillae crowded, to 40 mm long, bearing distichous flowers; female rachillae to 15 cm, bearing up to 27 pairs of flowers. Mature fruit round to ovoid, 1011 mm diameter, covered with 78 vertical rows of pale greenish scales with pale brown margins. Seeds 7 mm×6 mm×5 mm, deeply pitted.
Growth and development
After germination, forked leaflets are produced, followed by leaves with regularly arranged leaflets. By the third year an aerial stem may be produced. If clustering, leafy suckers normally remain dormant, rarely 23 stems elongate at the same time. First flowering takes place about the 6th year after sowing.
Other botanical information
Scattered clumps with spineless leafsheaths occur among normal clumps with spiny sheaths. These should be selected for plantations for ease of harvesting canes. Some plants are singlestemmed throughout their life, whereas others produce several suckers.
Ecology
C. subinermis is found only along the coast. It grows on sandy soils derived from sandstone on hill slopes, raised sandy beaches and also on alluvial soils on flat land in coastal dipterocarp forest but not in Casuarina forest. It has also been recorded in forest on ultramafic igneous rocks.
Propagation and planting
Soon after harvest, the fruits are crushed and rubbed over quarterinch wire mesh and under running water to remove the scaly pericarp and the fleshy sarcotesta. The cleaned seeds are then spread in seedbeds filled with either loam, loam and sawdust or sawdust only, and watered twice a day. The beds are also sprayed with fungicide to prevent fungal attack. After planting, most seeds germinate in about one month, although some do not germinate until 1.5 years later. Seedbeds are given full overhead shade.
When seedlings are 5 cm tall, they are potted into polybags 15 cm deep and about 15 cm in diameter filled with forest topsoil. They are watered twice a day and 50% overhead shade is provided by netting. Fertilizers and fungal sprays are applied whenever necessary. Seedlings are ready for planting 12 months after potting into polybags. They may be planted under rubber trees or in secondary forest at a spacing of 2 m×10 m or wider. In secondary forest, lanes 3 m wide are cut and staked before planting. Canopy manipulation is carried out so that sufficient light reaches the seedlings to stimulate early stem elongation.
Husbandry
Apart from initial weeding and canopy opening, little maintenance is required.
Diseases and pests
Fungal diseases occur in seedlings but large plants are normally free from attack. Elephants uproot the plants and eat the cabbage. Small trials of C. subinermis , planted inland, were completely destroyed by Chalcosoma atlas , a beetle whose larvae bore down the apex of the cane and destroy the meristem.
Harvesting
The cane is cut at the base and pulled. Only the length reachable by the harvester is extracted and the rest left behind to rot. The leafsheaths are removed and the cane is then cut into 3.5 m long poles.
Handling after harvest
After harvesting, canes are washed and cleaned before being boiled in diesel, after which they are stood upright to dry in the sun. When dried to a moisture content of less than 20%, the canes are not attacked by staining fungi or borers. The nodes are then trimmed before bundling.
Genetic resources and breeding
The Research Centre of the Forest Department, Sabah is at present setting up a provenance trial with provenances from throughout Sabah. Future selection should be for individuals with long internodes, thornless leafsheaths and multiple stems.
Prospects
There is a scarcity of high quality largediameter canes throughout SouthEast Asia, due to extensive and intensive harvesting. The prospects for commercial planting of C. subinermis along the coast are very good because of the clustering nature of the plant, providing for multiple harvests. Trials are required in areas away from the sea, and an effective treatment against beetle attack needs to be established.
Literature
- Dransfield, J., 1984. The rattans of Sabah. Sabah Forest Record No.13. Forest Department, Sabah. pp. 9698.
- Statistics Department Sabah, 1988. Sabah export of unprocessed whole rattan canes (19791988).
Authors
P.S. Shim
