Clustered (?) slender palm climbing to 10 m. Stems without sheaths 6-10 mm in diameter, with 8-15 mm; internodes ± 15 cm long. Leaf sheaths striate, moderately to sparsely armed with caducous black spines, particularly concentrated and persistent on ocrea, often sloughing off to leave raised, triangular, blister-like scars, sheath sometimes becoming bare at base; white caducous indumentum present on mature sheaths, profuse on young sheaths; ocrea horizontally truncate, without conspicuous lobe, extending to ± 3 cm. Leaves sessile, or with a very short (less than 2 cm) petiole; rachis up to 60 cm long, unarmed; cirrus 35-45 cm long, unarmed; acanthophylls, 1.0-1.8 cm long. Leaflets composed of 2-4 folds, broadly lanceolate, ovate or sigmoid, 7-15 on each side of the rachis, 10-15 cm long, 2.5-5.0 cm broad at the widest point, with 2 or more prominent veins, leaflets margins sparsely armed with rather fine spines. Flower and fruit unknown.
This species is recorded as occurring in swamp forest only. Oncocalamus wrightianus is distinct from all the other species in this genus by its slender nature and relatively broad, sigmoid leaflets. This species was recently reduced to synonymy by Tuley (1995), who suggested that this species represented a juvenile form of Oncocalamus mannii. However, this is not the case as the juvenile leaves of the members of this genus are strongly bifid. More extensive field collections, particularly those of fertile material, are needed to enable a more detailed description of this taxon to be made. Vulnerable (VU) due to its restricted range and habitat loss.
Native to, Benin, Nigeria
Oncocalamus wrightianus is known only from southern Benin and Nigeria, extending eastwards to the Niger Delta.