Calamus optimus (PROSEA)
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Introduction |
Calamus optimus Beccari
- Protologue: Nelle foreste di Borneo: 610 (1902).
- Family: Palmae
- Chromosome number: 2n= unknown
Vernacular names
- Indonesia: rotan taman (Central Kalimantan), suko (South Kalimantan), rotan sego (Sumatra: Bengkulu)
- Malaysia: uwai telong, wi sego (Sarawak).
Origin and geographic distribution
C. optimus is found in Borneo (Sabah, Brunei, Sarawak, Kalimantan) and possibly also in Sumatra (southern Bengkulu). It has apparently been cultivated by villagers in Sampit and Muara Aman (Central Kalimantan) ever since C. caesius Blume has been cultivated in that area.
Uses
In Sarawak the cane is used in the making of mats, for weaving, to bind furniture and as cordage. In Central and South Kalimantan the split cane is important in commerce for the same purposes.
Production and international trade
The canes of C. optimus are apparently treated in the same way as C. caesius , and are sold mixed with the latter species. A plantation has been established by the Kelabit people in Pa Tik (Sarawak); villagers cultivate a few clumps for domestic use of the cane.
Properties
The cane has a quality similar to that of C. caesius , except that it is generally slightly larger in diameter. It is a resilient and durable cane with a smooth golden surface. Its uniform texture makes it particularly suitable to be split into fine strips (chair cane). The quality of the cane is adversely affected by poor processing; it also depends on factors such as age, moisture content and light conditions during growth.
Description
Moderately robust, clustering rattan reaching 50 m, dioecious. Stem without leafsheaths 15 mm in diameter, with sheaths c. 30 mm; internodes to 15 cm, sometimes longer in juvenile stems. Leaf up to 2.5 m long, including a cirrus of up to 1.5 m; leafsheaths dark green, armed with scattered, large, convexbased, triangular, flattened, blacktipped spines, and abundant caducous black scales; knee grossly swollen; ocrea small, c. 5 mm; petiole very short, scarcely exceeding 5 cm; leaflets up to 8 on each side arranged in 23 groups, narrow ovate or spathulate, the largest to 85 cm×11 cm, very stiff and coriaceous, somewhat plicate, on upper surface dark green, on under surface usually covered with buff indumentum, margin armed with short black bristles, transverse veinlets conspicuous. Inflorescences pendulous, the male similar to the female, the male inflorescence 1.5 m long with c. 10 partial inflorescences, each consisting of c. 20 slender, rather upcurved rachillae, 2.5 cm long; each rachilla bearing c. 26 male flowers; flowers ellipsoid, c. 3 mm long. Ripe fruit ellipsoid, 15 mm×10 mm, tipped with a short beak to 1.5 mm long, covered in 15 vertical rows of pale yellowishbrown scales. Seed to 10 mm×8 mm; endosperm deeply ruminate. Seedlingleaf with 2 parallel leaflets joined together for much of their length.
Growth and development
Studies on growth have been conducted in Sarawak since 1982 but no results are available.
Other botanical information
C. optimus is closely related to C. caesius . The gross morphology of the inflorescences is very similar. The main differences are that C. optimus is more robust, its leafsheaths are covered with more massive spines and black scales, its leaflets are very much larger, and the undersurface of the leaflets is covered by buff rather than by white indumentum.
Ecology
C. optimus grows in lowlands in primary mixed dipterocarp forest; once found growing well in Sabah at 300 m in secondary forest dominated by Dillenia suffruticosa (Griff.) Mart.; elsewhere known in scattered localities.
Propagation and planting
Propagation is by seeds. C. optimus is planted in the same way as C. caesius except that it can be planted in drier soils. Nursery and fertilizer trials by the Forest Department, Sarawak, are in progress.
Husbandry
Postplanting maintenance is relatively simple. The soil around the plants should be kept weedfree manually for 23 years. Overhead shade should be manipulated at about sixmonthly intervals for 23 years to ensure sufficient light for the seedlings to grow vigorously. About 50% light/shade conditions are ideal for rattan growth. A path 1 m wide may be maintained in the planting row to allow easy access and maintenance. NPK compound fertilizer needs to be applied every 6 months if soil conditions are poor.
Diseases and pests
In the nursery, disease and pest attack is usually minimal if strict nursery hygiene is observed. However, seedlings may suffer leafspot diseases caused by Curvularia, Colletotrichum, Phomopsis and Pestalotiopsis species. Severely infected leaves will dry up. These diseases can be controlled by applying fungicides. Leaf blight caused by Colletotrichum gloeosporioides is more serious and may kill the seedlings in a few weeks. It can be controlled with fungicide applied at 10day intervals. In the field, individual shoots may be attacked by rats, squirrels, porcupines and an unidentified weevil. In Sabah, elephants are known to pull out seedlings or feed on the shoots. Wild boars will uproot seedlings as they forage for roots and worms.
Harvesting
Mature canes can be harvested selectively in the eighth year after planting. Harvesting is carried out by cutting the rattan cane at about 30 cm from the base, pulling the cane down out of the canopy as much as possible, removing the leafsheaths by twisting the cane around a tree trunk or hitting it with a knife. The cane, divested of its sheaths, is then cut into lengths of about 6 m and bent, and tied in bundles of 100 pieces. Inevitably, variable portions of canes will be left in the canopy and cannot be pulled out because of entanglement with tree branches. More efficient mechanical methods of harvesting have yet to be developed for large commercial plantations.
Handling after harvest
Canes should be processed soon after harvesting, in order to maintain their quality. Postharvest treatment of canes involves washing to remove mud and remaining leafsheaths, drying, and sulphur fumigation to prevent attack by diseases and pests and to improve cane colour.
Genetic resources
C. optimus has been collected and planted in a number of botanic gardens and arboreta in several countries. Recently, different provenances of this species have been collected for provenance trials by the Sabah Foundation in Sabah, Malaysia.
Breeding
No breeding work has been carried out on C. optimus . Primary selection and provenance trials are needed before a breeding programme can be initiated.
Prospects
Supply of C. optimus from natural forests has been dwindling fast, especially in Malaysia, due to overexploitation and destruction of its natural habitat when forest is converted for agriculture. Rich alluvial flats and other fertile land where C. optimus used to thrive best have practically all been converted to agricultural land. In Indonesia, fortunately, there is a long tradition of smallholders cultivating C. optimus, thus very significantly supplementing supply from the wild. Rattan cultivation has provided a very important source of income for large numbers of otherwise impoverished smallholders, especially in Kalimantan. Several Indonesian companies and Malaysian government bodies and private companies have also started cultivating this rattan on a commercial scale.
Literature
- Beccari, O., 1908. Asiatic palmsLepidocaryeae. Part 1. The species of Calamus. Annals of the Royal Botanic Garden, Calcutta 11: Plate 188.
- Dransfield, J., 1984. The rattans of Sabah. Sabah Forest Records No 13. Forest Department Sabah, Sandakan. pp. 100102.
- Johnson, D. (Editor), 1991. Palms for human needs in Asia. Balkema, Rotterdam & Brookfield. pp. 3773.
- Wan Razali Wan Mohd, Dransfield, J. & Manokaran, N. (Editors), 1992. A guide to the cultivation of rattans. Malayan Forest Records No 35. Forest Department, Kuala Lumpur. pp. 53, 84, 115.
Authors
J.P. Mogea
