Clustered, slender to moderate palm climbing to 20 m, often branching sympodially at the base. Stem without sheaths, 1.0-2.8 cm in diameter, with, 1.2-3.5 cm; internodes 8-20 cm long, more commonly 15-20 cm. Leaf-sheaths varied in armature from almost unarmed to densely spiny, with a distinct horizontal, sometimes folded, knee below the petiole; spines dark brown or black, triangular, flattened at base, up to 3 cm long, clusters of upward pointing spines often concentrated around the leaf-sheath mouth to form a conspicuous cleft; mature sheaths with brown or grey indumentum; ocrea to up 12 cm long, usually 8-10 cm, 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. Leaves ecirrate, up to 1.75 m long, usually 1.2-1.5 m; petiole to 20 cm long, rounded abaxially, concave adaxially, ± 5 mm broad, variously armed with large black spines to 3 cm long and small recurved black thorns; rachis triangular in section distally armed as the petiole, spines becoming sparse distally; leaflets up to 30 on each side of the rachis, sub-equidistant to equidistant proximally, grouped in 3's to 6's distally, linear-lanceolate, finely acuminate to apiculate at apex, bluntly compact at the base, up to 35 cm long by 2 cm broad at the widest point, concolourous with slightly darker green upper surface, leaflet margins, main vein and secondary nerves bristly throughout. Flagellum up to 3.5 m long by 4 mm wide at the base, decreasing very gradually above, armed with small recurved thorns. Male and female inflorescences similar, up to 3.5 m long, with 1-4 partial inflorescences and a long terminal sterile flagellum; axis and bracts armed throughout with reflexed, solitary or grouped black prickle-like spines; bracts tightly sheathing, up to 70 cm long with an expanded, papyraceous limb ± 5 cm long; partial inflorescences to 40 cm long, with up to 15 or more rachillae on each side, subtended by bracts 2 cm long (1 cm. exposed), with mouths 7 mm wide and with a short triangular limb to 4 mm; rachillae up to 7 cm long, arcuate, arranged distichously; bracts distichous, dull brown in colour, ciliate-hairy around the mouth. Male flowers solitary, distichous, with a minute involucre to 1 mm long; calyx 4 mm long, tubular for 3 mm, with 3 short, triangular, striate lobes; corolla-lobes to 7 mm long by 2 mm wide, fused at the base for 1 mm, widely diverging at anthesis; stamens to 4 mm long, minutely epipetalous, with filaments up to 3 mm long, anthers 3 mm. long, medifixed; pollen yellow. Sterile male flower very similar to fertile male but slightly shorter and narrower. Female flower with calyx tubular at first and then splitting as ovary increases in size, lobes 3 mm long; 5 corolla-lobes by 2 mm, with 6 minutely epipetalous flattened staminodes; ovary ± 5 mm long by 2.5 mm wide, tipped by 3 stigmas 1 mm long, markedly recurved at anthesis. Fruit at maturity to 1.5 cm, by 1 cm with a short beak up to 2 mm tipped by remains of the style, with 17-20 vertical rows of scales. Seed flattened laterally, 9 x 8 x 5 mm, with sarcotesta 1 mm thick when dry; endosperm homogeneous, embryo basal. Germination adjacent-ligular; eophyll pinnate.
The fact that Calamus in Africa has been the cause of some taxonomic problems has been undoubtedly due to the recognition of poorly defined infraspecific variation. However, from recent examination of herbarium specimens and field observations, it is clear that Calamus in Africa is represented by a single polymorphic species. Some past splitting included: Calamus akimensis Type:-GHANA, Calamus barteri Type:-NIGERIA, Calamus falabensis Type:-SIERRA LEONE, Calamus heudelotii Type:-GAMBIA, Calamus laurentii Type:-DEMOCRATIC REPUBLIC OF CONGO, Calamus leprieurii Type:-GAMBIA, Calamus perrottetii Type:-SENEGAL, Calamus schweinfurthii Type:-SUDAN.
Heimisch in, Angola, Benin, Burundi, Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea Bissau, Guinea, Liberia, Nigeria, Rwanda, Senegal, Sierra Leone, Tanzania, Togo, Uganda, Ivory Coast, South Sudan
The most widely distributed of the rattans of Africa and is distributed across the humid forest zone of Africa; from the Gambia and Casamance in Senegal, southwards to northern Angola and Zambia and eastwards to south Sudan and Uganda. It has a strong preference for swamp and riverine forest, and is rather less common in areas with high rainfall. As such, this species is relatively rare in the Guineo-Congolian forest of Cameroon and Gabon. This species is more common in drier gallery forest found in the transition zones between Sudanian savanna woodland to the north of the Guineo-Congolian forest formation, and Zambezian savanna woodland to the south. It occurs in lowland forest areas in west and central Africa at altitudes less than 500 m and in the higher altitude regions of east Africa at 1500 m. It is usually found in forest under a canopy, but also occurs in open areas where it often forms dense thickets.