Calamus deerratus (PROTA)
Calamus deërratus G.Mann & H.Wendl.
- Protologue: Trans. Linn. Soc. London 24(3): 429 (1864).
- Family: Arecaceae (Palmae)
- Calamus barteri Drude (1895),
- Calamus heudelotii Drude (1895),
- Calamus leprieurii Becc. (1902),
- Calamus perrottetii Becc. (1902),
- Calamus schweinfurthii Becc. (1902),
- Calamus laurentii De Wild. (1904),
- Calamus akimensis Becc. (1908),
- Calamus falabensis Becc. (1908).
- Rattan, rattan palm (En).
- Rotin (Fr).
- Rotim (Po).
Origin and geographic distribution
Calamus deërratus is the most widely distributed of the African rattans and is distributed across the humid forest zone of Africa, from Gambia and Senegal eastwards to southern Sudan, Uganda and Tanzania, and southwards to northern Angola and Zambia. It is not cultivated.
Throughout West Africa in particular, Calamus deërratus has a wide range of uses for furniture, construction and basketry. Whole stems are also made into walking-sticks and musical instruments. In Ghana they are woven into screens for fencing. In Nigeria stems of Calamus deërratus were formerly supplied to prisons for workshop activities and the rehabilitation of prisoners. Whole stems were widely used for building houses and fences in Nigeria as well as in Ghana. In Zambia and Uganda in the absence of large-diameter stems, rattan furniture frames are made of two or three stems of Calamus deërratus joined together. Both whole and split stems are used to make traditional suspension bridges and foot-loops for climbing palm trees. Split stems are made into a wide range of products, such as baskets, chair seats, bow strings, and fish traps and weirs, and they are used for tying house frames, rafters, thatch and fences. In the continental region of Equatorial Guinea, for instance, they are used in the fabrication of temporary market baskets. They have also been used for the fabrication of tie-ties for the staking of yams. In Nigeria split stems were formerly used to tie timber trees together prior to floating them downriver. The stem bark makes a strong rope. In Sierra Leone, the stem bark is twisted into little sponges and used to clean pans. In Ghana the leaves are often used for thatching. The leaf sheath may be peeled off and twisted to make a rough rope.
The apical bud (palm heart) is eaten in Sierra Leone and Ghana and roasted young shoots are eaten in Ghana. Ash from burned roots is used as a kitchen salt in Guinea and Ghana. In Senegal the leaves are grilled over a fire and then macerated, and the liquid is drunk to promote weight loss; the same preparation is also given for the treatment of oedema caused by vitamin deficiencies.
Production and international trade
Calamus deërratus is locally traded in West Africa, East Africa and southern Africa (Zambia and Zimbabwe), but there are no reports of trade in Central Africa. It is not internationally traded.
Calamus deërratus is only utilized in the absence of other rattan species with more desirable qualities with respect to flexibility and durability. Throughout its range, its stems are considered inferior to other lianous palms, as they are not as robust as many of the larger Laccosperma spp., and less flexible than many Eremospatha spp. At 12% moisture content stems from Nigeria had a modulus of rupture of 41 N/mm² and a modulus of elasticity of 3400 N/mm². Per 100 g dry matter the stem contains: energy 1023 kJ (244 kcal), protein 6.0 g, fat 1.2 g, carbohydrate 67.1 g, fibre 19.0 g, ash 12.0 g, Ca 200 mg, P 500 mg, Fe 25 mg. Air-dried samples of the stems in Nigeria were recorded to contain per 100 g: water 15.0 g, energy 1324 kJ (316 kcal), protein 4.6 g, fat 0.6 g, carbohydrate 77.8 g, ash 1.9 g, Ca 138 mg, Mg 52 mg.
Adulterations and substitutes
The stems of Calamus deërratus are not as widely used as those of Laccosperma and Eremospatha spp. However, the use of Calamus deërratus increases in the absence of other rattans and because Calamus deërratus also contributes to other household needs, aside from a wide range of construction and weaving applications.
Dioecious, clustering, slender to moderately robust rattan palm, climbing up to 20 m high, often branching sympodially at the base, forming dense clumps; stem erect, prostrate or scandent, up to 30 m long, 7–30 mm in diameter without sheaths, 12–35 mm with sheaths, internodes (8–)15–20 cm long. Leaves pinnately compound, up to 1.5(–1.75) m long; sheath varied in armature from almost unarmed to densely covered with triangular, dark brown or black spines up to 3 cm long, mature sheath with brown or grey indumentum; ocrea 8–10(–12) cm long, dry, papyraceous, tongue-shaped, often longitudinally splitting and reflexed, becoming unrecognisable, armed on the margins with spines more pale and bristle-like than those on the leaf-sheath, rarely unarmed; flagellum up to 3.5 m long, armed with small recurved thorns; petiole up to 20 cm long, rounded abaxially, concave adaxially, variously armed with large black spines up to 3 cm long and small recurved black thorns; rachis armed as petiole, spines becoming sparse distally, cirrus absent; leaflets up to 30 on each side of the rachis, linear-lanceolate, up to 35 cm × 2 cm, bluntly compact at the base, finely acuminate to apiculate at the apex, single-folded, concolorous or with slightly darker green upper surface, with bristles on leaflet margins and veins. Inflorescence axillary; male and female inflorescences similar, up to 3.5 m long, with 1–4 partial inflorescences and a long terminal flagellum; axis and bracts armed throughout with reflexed, solitary or grouped black spines; bracts tightly sheathing, up to 70 cm long with an expanded, papyraceous limb c. 5 cm long; partial inflorescences up to 40 cm long, with up to 15 or more rachillae on each side, subtended by bracts c. 2 cm long; rachillae up to 7 cm long, arcuate, arranged distichously; bracts distichous, dull brown in colour, ciliate-hairy around the mouth; in male inflorescence flowers solitary, in female inflorescence flowers in pairs of 1 female flower and 1 sterile flower. Flowers unisexual; male flower symmetrical, with minute involucre to 1 mm long, calyx tubular at base, 4 mm long, 3-lobed, corolla with 3 valvate lobes up to 7 mm long, fused at the base for c. 1 mm, stamens 6, pistillode minute or absent; sterile flower very similar to fertile male one but slightly shorter and narrower and with empty anthers; female flower with calyx tubular at first and then splitting as ovary increases in size, lobes c. 3 mm long, corolla with 3 valvate lobes c. 5 mm long, staminodes 6, epipetalous, ovary c. 5 mm × 2.5 mm, tipped by 3 stigmas c. 1 mm long, recurved at anthesis. Fruit globose, up to 2 cm × 1 cm, with a beak up to 2 mm long tipped by remains of the style, with 16–21 vertical rows of scales, 1-seeded. Seed flattened laterally, c. 9 mm × 8 mm × 5 mm.
Other botanical information
Calamus comprises about 370 species, distributed from West Africa to South-East Asia, Australia and Fiji. Recent examination of herbarium specimens and field observations made it clear that Calamus in Africa is represented by a single polymorphic species. The fact that Calamus in Africa has been the cause of some taxonomic problems has been due to the recognition of poorly-defined infraspecific variation.
The cross section of the stem shows three distinct regions: epidermis, cortex and central cylinder. The epidermal cells are rectangular, 15–26 μm long and 7–11 μm wide, with stomata in the cuticular layer. Two layers of unlignified parenchyma cells below the epidermis are assumed to be the hypodermis. The cortical zone is 6–10 cells wide, the cells being of varying sizes, rectangular with rounded corners, lignified and interconnected. The cortex is interspersed with small fibre bands. The central cylinder is composed of vascular bundles embedded in ground parenchyma. The outer vascular bundles of the central cylinder are incomplete whilst the inner ones are complete and diffusely arranged. The vascular bundles consist of conducting tissue (xylem and phloem), surrounded by a fibre sheath and parenchyma. A complete vascular bundle contains one metaxylem vessel with a diameter of 68–337 μm, protoxylem consisting of a cluster of 2–5(–10) vessels, and two phloem fields each containing 4–6 sieve tubes. The fibre sheath surrounding the bundle is relatively extensive in peripheral vascular bundles but forms only a small border in the inner vascular bundles. The fibre cells are 0.6–4.2 mm long and 5.8–34.8 μm wide, with a lumen width of 2.9–29 μm and a cell wall thickness of 1.5–20.37 μm. The ground tissue parenchyma is polygonal and rectangular in shape and corresponds to the ‘net-like’ type in transverse section and in longitudinal section resembles ‘coins in a pile’.
Growth and development
Calamus deërratus climbs by means of flagellae, arising directly from the sheath. In experiments in Ghana eleven-month old seedlings had a growth rate of about 7 cm in 20 weeks. In Benin flowering and fruiting is in December. All Calamus species are pleonanthic, i.e. the stems do not die after flowering.
Calamus deërratus has a strong preference for swamp and riverine forest and is less common in areas with high rainfall. As such, it is relatively rare in the Guineo-Congolian forest of Cameroon and Gabon. It is more common in drier gallery forest in the transition zones to the Sudanian savanna woodland in the north, and to the Zambezian savanna woodland in the south. Calamus deërratus occurs in West and Central Africa up to 500 m altitude, and in East Africa up to 1500 m altitude. It is usually found in forest under a canopy, but also occurs in open areas where it often forms dense thickets. Swamp forests with Calamus deërratus in Uganda are prone to seasonal fires, which is partly aggravated by the rattan harvesters leaving the upper parts of the rattan stems in the canopy.
Propagation and planting
Seeds germinate better when the sarcotesta has been removed, but soaking of the seeds in concentrated sulphuric acid or ethyl alcohol is detrimental. In Ghana Calamus deërratus has been successfully propagated using rhizomes, with about 20% sprouting.
Calamus deërratus is harvested solely from the wild. Indigenous management systems for the rattan resource in Africa are unknown, and, throughout its range, rattan is considered an open-access resource; there are very few, if any customary laws regulating its harvest. This is mirrored in the lack of national legislation for most countries.
The conditions and circumstances under which rattan species in Africa are harvested and transported are remarkably consistent. The majority of the harvesting for commercial trading is undertaken by individuals as a secondary source of income. Despite the recognised capital returns of rattan harvest and sale, the unpleasant and difficult nature of rattan harvesting means that most harvesters state that they would prefer to concentrate on their primary occupations given the opportunity. Most rattan harvesters are local, people from elsewhere often have to pay a small amount to the local chief.
Handling after harvest
Processing of raw cane entails the removal of the epidermis (skin) from the stem with a knife and the drying of the raw cane prior to its use. Immature stems, or the very apex of mature stems, where the leaf sheath is also present, are not used and are often left or discarded at the time of harvest. Drying is usually done in the open air. This rudimentary way of processing is not only labour intensive, but also results in inferior quality cane.
Calamus deërratus has a wide distribution and is not considered threatened, according to IUCN criteria. Although many rattan species respond well to selective logging activities, logging has also resulted in increased rattan exploitation. The development of a wide network of logging roads throughout many forest areas in West and Central Africa has enabled greater access, and logging trucks are often responsible for the transport of harvested rattan.
Calamus deërratus will remain a very useful local source of rattan, although it is usually considered inferior to other African rattan species. In general, there is growing interest in the rattans of Africa owing to their importance in the livelihoods of rural as well as urban people. Research on rattans in Ghana, Nigeria and Cameroon has shown that cultivation is ecologically feasible, but hampered by socio-economic and socio-cultural factors such as land tenure and perceptions of unlimited wild supplies.
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Sources of illustration
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Correct citation of this article
Sunderland, T.C.H., 2011. Calamus deërratus G.Mann & H.Wendl. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands.
Accessed 6 October 2022.