Oncocalamus mannii (H.Wendl.) H.Wendl.

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/95366508/95366515

Conservation

LC - least concern

Distribution

O. mannii is restricted from southern Cameroon to Gabon.

Biology

O. mannii is common in open areas, roadside and forest gaps. This species responds extremely well to selective logging and is a common component of regrowth vegetation.

General Description

Clustered slender to moderate palm climbing to 15-30 m. Stems without sheaths 8-16 mm in diameter, with 12-28 mm; internodes 12-18 cm long. Leaf sheath longitudinally striate, dark green, tan, often dull crimson brown on young sheaths, moderately to sparsely armed with brown-black spines, concentrated and persistent on the ocrea, spines often sloughing off elsewhere on sheath to leave conspicuous, raised, circular, blister-like scars; thin, white caducous indumentum present on mature sheaths, particularly dense on young sheaths and juvenile individuals; ocrea ± truncate or saddle-shaped with a 0.5-1.8 cm high rounded lobe opposite the rachis, armed as the leaf sheath, spines concentrated at ocrea margin, extending ± 2 cm. Spear leaf deep orange to bright crimson. Juvenile stems up to 6 m long, with sheaths, <1 cm in diameter, leaves sessile or with a short (1.5 cm) petiole, strongly bifid, eventually becoming pinnate, up to 30 cm long and 4.5-6 cm broad at the widest point and with a 60 cm long cirrus emerging from the centre; elaminate rachis often present at base of stem, up to 2.5m long. Leaves on mature stems sessile, or with a short (<2.5 cm) flattened petiole; rachis 1-1.2 m long, abaxially rounded, adaxially concave, becoming circular in cross section distally, armed as the leaf sheath, spines particularly profusely armed on underside, although often smaller than those on the sheath; cirrus 1-1.5 m long, unarmed; leaflets, 25-35 on each side of the rachis, linear-lanceolate, to mildly sigmoid, broadly attenuate at the base, apex somewhat acuminate, 16-32 cm long, 1.8-2.5 cm broad at the widest point, ± concolorous, dark green, armed along the margins with robust spines particularly at base of leaflet, single-nerved, with 6-7 conspicuous secondary nerves on each side; lowermost leaflets smaller than the rest, held vertical to rachis; acanthophylls up to 1.5 cm long. Inflorescences in successive axils 3-5m from stem apex; peduncle 8-15 cm long, hemispherical in cross section; prophyll 3-8 cm long; peduncular bracts 2-4, 2.5-4 cm long; rachis up to 0.8-1m long, pendulous; rachis bracts 2.5-4 cm long; rachillae circular in cross section, 15-28 cm long, pendulous, bracts deep-bright crimson prior to anthesis, becoming dry, brown; prophyll subtending flower cluster 3-5 mm, conspicuously striate. Flower cluster with 1-3 central pistallate flowers subtended by 2 lateral cincinni of 1-2 pistillate and 2-3 staminate flowers; staminate flowers 5.5-6.5 mm × 2-3 mm; calyx ca.5.0 mm × 5.0-5.5 mm, including 1 mm-long stalk, tubular for ½ to ¾ of its length; corolla ca.5 mm long, tubular for the basal ±1 mm, cream/yellow; staminodial tube ca.2 mm long; anthers 0.8 mm × 0.3 mm; pistillode 1.5 mm × 0.7 mm, thin, tapering; pistillate flowers similar to the staminate flowers, up to 3-4 mm wide; ovary ca.2.5 mm × ca.1.5 mm. tipped by 1-1.5 mm long style. Fruitat maturity, globose to sub-globose, 1.8-2.2 cm × 1.6-2 cm, with 15-17 rows of vertical scales. Seed sub-globose 1.2-1.6 cm × 1.5-1.9 cm, with a narrow rounded depression below, covered with regular polygonal depressions, giving a distinctly warty appearance; sarcotesta white, thin (<0.5 mm).

Conservation

Least concern (LC)

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident