Calamus ovoideus (PROSEA)
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Introduction |
Calamus ovoideus Thwaites ex Trimen
- Protologue: Journal of Botany 23: 269 (1885).
- Family: Palmae
- Chromosome number: 2n= unknown
Vernacular names
- Sri Lanka: thuda rena (Sinhala, southwestern), sudu wewel (Sinhala, less commonly in southwestern), ma wewel (Sinhala, in trade, collective term for largediameter rattan).
Origin and geographic distribution
C. ovoideus is found only in Sri Lanka and is restricted to the southwestern part of the country.
Uses
In Sri Lanka split cane of C. ovoideus is used for weaving baskets, and whole canes for furniture frames. Split cane cores are used for less refined woven products.
Production and international trade
There is no trading of C. ovoideus outside Sri Lanka. A negligible amount of rattan products reach the tourist and export market. Locally all trade is within the southwestern part of the country. Products traded are mainly furniture and basketware for household and agricultural purposes, gem mining and the tea industry. At present C. ovoideus is scarce and is used mainly for basket making by villagers living close to forest areas. It is not available in sufficient quantity for furniture making. There is no estimate of the volume of rattan harvested. It is evident, however, that at present supplies are harvested illegally from forest reserves.
Properties
C. ovoideus has a smooth, pale brown cane with diameter of 3050 mm and internode length of 30 cm or more. The inner core is pale with hardly any soft pith. The cane is heavy and durable. It produces very good quality rattan for furniture frames and is well suited for good quality split rattan for basket work. The main factor affecting the quality of the cane is the harvesting of immature canes with high levels of moisture; these canes are apt to shrink and are easily attacked by insects.
Description
Clustering, robust, high climbing, dioecious rattan, with stems ultimately to 5070 m or more in length, the clump tending to have 210 wellspaced stems. Stem without leafsheaths, 3050 mm in diameter, with sheaths to about 4080 mm in diameter; internodes to 30 cm or more in length. Leaf to 34.5 m long including the sheath; leafsheath dull green, densely armed with oblique rings of flat triangular dark brown spines 10 mm long, interspersed with smaller spines and fine hairs; knee not prominent, marked by a neat ridge 1 cm wide and 1 cm high; petiole prominent, at least 50 cm long in adult climbing stems; rachis c. 2.54 m long, bearing scattered stout reflexed spines on the lower surface and grapnellike groups of reflexed spines containing 36 spines; distally the rachis extends into a cirrus c. 2 m long, bearing grapnellike groups of reflexed spines; leaflets c. 130 on each side of the rachis, arranged regularly in alternate pairs, lanceolate, up to c. 60 cm×2.5 cm, upper surface dark green, lower surface with a waxy coating giving the fronds a greygreen appearance. Inflorescence borne on leafsheaths, usually 68 at one time, pendulous, with stout peduncles; male and female superficially similar, with male to 22.5 m long, branching to 3 orders, female shorter to 1 m long, branching to 2 orders; bracts tightly tubular in proximal portion, sparsely spiny becoming funnelshaped in distal part; first order branches rather distant; rachillae slender, to 3 cm in the male, larger in the female; male flower pale yellow, c. 5 mm×3 mm; female flower larger than the male, each borne in a pair together with a sterile male flower. Mature fruit 1seeded, ovoid, c. 15 cm×10 cm, covered in small, neat, reflexed, dark green scales, deeply channelled in the middle with faintly orangebrown margins, turning pale yellowgreen when ripe. Seed c. 11.5 cm×7.5 cm, with an outer fleshy seedcoat (sarcotesta); endosperm ruminate, embryo basal. Seedlingleaf pinnate with c. 5 leaflets, spread out, about onethird the length of the whole leaf; upper surface of the leaflets light green with fine spines along the midrib and secondary veins; petiole and leafsheath sparsely covered with long narrow spines ending in a needlefine dark tip.
Growth and development
Seeds germinate after 2.53 months; after 1214 months seedling leaves may reach a height of 3050 cm and for 4 years the plant usually remains in a rosette state with seedling leaves reaching 2 m or more in height. By the 5th year the primary stem starts to develop and the first climbing whips begin to appear. By the 6th year the climbers may have grown up to 6 m long, and by the 7th year they attain a height of 810 m and suckers begin to develop. Information on growth is available from the earliest research trials started in 1985 on C. ovoideus underplanted in Pinus caribaea Morelet plantations. The trial plantings in natural forest show slower growth, indicating that the availability of light is an important factor. Observations of growth patterns of rattan plants in pine plantations suggest that a sudden increase of light may trigger the climbing habit. C. ovoideus flowers in April, fruits take 56 months to mature, ripening during September and October. Plants with 8 infructescences can bear up to 2000 fruits. Flowers appear to be pollinated by bees and seed dispersal seems to be effected mainly by polecats, civets ( Viverridae ), fruit bats, giant squirrels and leaf monkeys.
Other botanical information
The closely related Calamus zeylanicus Becc. often occurs together with C. ovoideus , has a similar ecology and is also a largediameter rattan suitable for cultivation.
Ecology
C. ovoideus occurs in lowland and lower montane rain forest areas below 1500 m altitude, with daylength 1012 hours, an average temperature of 27C, annual rainfall of 5000 mm evenly distributed throughout the year, and a relative humidity of 8090%. The soils here are mainly lateritic. The UNESCO system classifies this forest type as a tropical humid Sri Lankan rain forest of the IndoMalayan realm. C. ovoideus grows on welldrained slopes and is frequently found in forest gaps and other open sites. Juvenile clumps occur scattered in the forest undergrowth, but mature climbers are often associated with disturbance, natural or manmade, in forest gaps, logged forest and edges of clearings.
Propagation and planting
C. ovoideus is most effectively propagated from seed. It is difficult to propagate by removal of sucker shoots. Seed collection is tedious as the infructescence may be several meters above the ground and entangled with other vegetation. For fruit collection on a large scale, the infructescence is inserted into a bag and the stalk cut. This prevents the fruits from being scattered on the forest floor. The seeds are extracted by removing the fruit wall and the fleshy seedcoat. A single seed weighs about 1 g. The cleaned seeds must be kept moist until sown because they lose viability if they dry out. Seeds are sown in beds prepared with a mixture of soil and sawdust or a similar loose mixture. This enables germinated seed to be removed easily without damaging the root. Nursery beds are partially shaded to allow plenty of diffuse sunlight. The sown seeds are covered with a thin layer of soil. Deep shade and deep burial of seed tend to delay germination. Seeds begin to germinate between 2.53.5 months after sowing. The seedlings are potted after the first leaf has emerged. They are then kept in the shade and provided with plenty of moisture. Seedlings are ready for planting at 1214 months; however, survival rates are better when the seedlings are about 1618 months old. Seedlings are planted in natural forest, in forest plantations ( Pinus caribaea and mahogany), other tree crop plantations (rubber) and home gardens where a tree crop exists, because the plants need support. Trial plantings in Pinus caribaea plantations have shown the best results. If planting in a tree crop plantation, a spacing of 10 m×5 m is recommended to avoid tangling when the plants climb. In natural forest and home gardens selective planting can be done in forest gaps and close to a supporting tree.
Husbandry
When seedlings are planted in the natural forest, it is advisable to thin the canopy to allow more light, to speed up growth. For seedlings planted in forest plantations where weeds are abundant, patch weeding around the plant to keep it free of undergrowth in the first two years will improve survival. Canopy thinning about two years after transplanting is also recommended. If porcupine damage is severe, plant guards made of bamboo or wooden sticks can be used until the seedlings are established. In fireprone areas such as pine plantations, the rattan must be protected by growing fire breaks as they are easily destroyed. Fertilizer application is recommended if planting sites are degraded reforested areas such as pine plantations. A regular NPK fertilizer or urea has been used successfully.
Diseases and pests
Few diseases and pests have been reported. There have been instances when rats have clipped off the new leaves of seedlings in the nursery. Damage by porcupines, once the seedlings are planted out, has been especially severe in pine plantations.
Harvesting
Rattans are tugged down from the canopy and the leafsheaths pulled off the stem with the help of a knife. Often a considerable part of the cane may be left behind in the canopy. The cane is then cut into lengths of 510 m and transported. The canes are dragged along on the long journey out of the forest, which causes some damage. Current methods of harvesting are very wasteful.
Handling after harvest
Postharvest treatment is minimal. The canes are cleaned of the remains of leafsheaths. Villagers prepare canes for their own use by further cleaning, sun drying, splitting and coring. Otherwise, the raw rattan is cut into lengths and transported to the nearest town with commercial craft establishments. Here the canes may be further air or sun dried and debarked in order to obtain a clean cane with uniform dimensions. Canes used for furniture are smoothed with sand paper and coated with coconut oil to produce lustre. Fungal staining and attack by powderpost beetles are very common. Processing is very simple and there is an urgent need to develop better methods to minimize waste and increase the quality of the cane.
Genetic resources
Although C. ovoideus is the most prized Sri Lankan rattan species, there has been no systematic collection of plant material for adequate representation of the species. The several hundred thousands of seedlings raised in the last 7 years by the Forest Department are from a narrow genetic base of a few clumps in the Sinharaja Forest. This is due to the scarcity of mature clumps, and so far this is the only known large seed source (about 6000 plants) accessible for regular supply. C. ovoideus has been recently introduced to the botanic gardens in Peradeniya. Seeds have been sent abroad on various occasions.
Breeding
No breeding work has been attempted. If such programmes are to be initiated, the scarcity of seedbearing mature clumps will be a serious impediment. Major breeding objectives should be to select for quick growth and early formation of suckers.
Prospects
C. ovoideus is a rattan species with many desirable characteristics. It is of large diameter, with a heavy durable cane, a clustering habit and indivual stems can produce large quantities of seed annually. Because of its excellent quality and clustering habit, there is great potential for developing the species for plantation establishment in the Asian region. It is currently under trial in Malaysia. Its restricted distribution i.e. to the southwestern part of Sri Lanka where it occurs in fragmented rain forests, makes it an exceptionally endangered resource. Efforts should combine protecting wild stocks and stepping up cultivation. In a network of selected natural forest sites, mature climbers must be allowed to reach the seedbearing stage both by stricter legislation and by enlisting support from local people. Planting material should be obtained from as wide a genetic base as possible and selection done for desirable characters. So far, planting has been done almost entirely in stateowned forests with little or no maintenance, resulting in poor survival and growth. Greater success may be ensured if craft workers and entrepreneurs take up cultivation on private land. Seed material must be distributed to other countries in the region on a systematic basis. Techniques should be developed for propagating C. ovoideus by tissue culture.
Literature
- de Zoysa, N.D. & Vivekanandan, K., 1989. Recent progress in rattan research in Sri Lanka. In: Rao, A.N. & Vongkaluang, I. (Editors): Recent research on rattans. Proceedings of the International Rattan Seminar, Chiangmai, 1214 November 1987. Faculty of Forestry, Kasetsart University, Thailand and International Development Research Centre, Canada. pp. 2532.
- de Zoysa, N.D. & Vivekanandan, K., 1991. The bamboo and rattan cottage industry in Sri Lanka: livelihoods in danger. Forestry Information Service, Forest Department, Sri Lanka. p. 93.
- Trimen, H., 1898. A handbook to the flora of Ceylon. Part 4. Dulau, London. p. 335.
Authors
N. de Zoysa
