1. Family: Arecaceae Bercht. & J.Presl
    1. Oncocalamus (G.Mann & H.Wendl.) H.Wendl.

      1. This genus is accepted, and its native range is S. Benin to W. Central Tropical Africa.

    [PW]
    Vernacular
    Common names numerous (Sunderland 2001).
    General Description
    Clustered, spiny, high-climbing, pleonanthic, monoecious, rattan palms. Stem eventually becoming bare, circular in cross-section, with long internodes. Leaves pinnate, bifid in juveniles, with a terminal cirrus; sheath strictly tubular, bearing scattered, black, bulbous-based, triangular, brittle spines and scattered, thin, caducous indumentum; ocrea conspicuous, tightly sheathing, neatly truncate, armed as the sheath; knee absent; petiole present but usually very short, absent in mature flowering stems; rachis armed with scattered spines as the leaf sheath; cirrus bearing neat pairs of reflexed acanthophylls; leaflets few to numerous, usually single-fold, sometimes with 2 or more folds, entire, acute, linear, lanceolate or somewhat sigmoid, regularly arranged, usually armed along the thickened margins with robust spines, midribs evident, other large veins rather distant, transverse veinlets conspicuous; proximal few leaflets sometimes smaller than the rest, heavily armed and reflexed across the sheathed stem. Inflorescences branched to 1 order; peduncle enclosed within the leaf sheath and emerging from its mouth, ± hemispherical in cross-section; prophyll tubular, tightly sheathing, 2-keeled, 2-lobed at its tip, much shorter than the sheath; peduncular bracts ca. 4, ± distichous, tightly sheathing at first, later splitting longitudinally, each with a short triangular lobe; rachis longer than the peduncle; rachis bracts like the peduncular, rather close; first-order branches pendulous or spreading with a basal 2-keeled tubular prophyll and numerous distichous, short, tubular, somewhat inflated, striate bracts, each enclosing a flower cluster, after anthesis eventually irregularly splitting and tattering; flower cluster partially covered by a tubular 2-keeled prophyll and consisting of up to 11 flowers arranged in a group with a central 1 or 3 pistillate flowers and 2 lateral cincinni of 2–4 staminate flowers, each flower, apart from the central pistillate bearing an open, spathulate, 2-keeled, prophyllar bracteole (the precise arrangement of the flowers not yet understood). Staminate flowers symmetrical; calyx membranous, striate basally, stalked, tubular, with 3 short triangular, apiculate lobes; corolla apparently only slightly exceeding the calyx, divided almost to the base into 3 elongate, striate, valvate petals; stamens 6, filaments united to form a thick, fleshy androecial tube, free from the corolla, tipped with 6 shallow lobes, bearing pendulous, rounded, latrorse anthers on the inside; pistillode very narrow, conical, slightly exceeding the androecial tube. Pollen ellipsoidal, bi-symmetric; aperture a distal sulcus; ectexine tectate, very finely perforate, interspersed with very small spinulae, aperture margin similar; infratectum columellate; longest axis 23–29 µm [1/4]. Pistillate flowers superficially very similar to the staminate except slightly broader; the calyx and corolla similar; staminodal tube bearing minute empty anthers; gynoecium tricarpellate, triovulate, ± ellipsoidal, covered in reflexed scales, style long, narrow, 3-angled, ovule form unknown. Fruit ± spherical, stigmatic remains minute, conical, apical; epicarp covered in vertical rows of rather thin reflexed scales, mesocarp very thin, almost obsolescent at maturity, endocarp not differentiated. Seed single, basally attached with an oval hilum, covered with a ?thick sarcotesta and endosperm homogeneous, laterally deeply penetrated by a smooth-margined mass of inner seed coat; embryo lateral opposite the intrusion. Germination and eophyll unknown. Cytology not studied. Clustered, spiny, moderate to high-climbing, pleonanthic, monoecious rattan palms. Stem circular in cross section, with short to medium internodes; sucker shoots axillary. Leaves pinnate, strongly bifid in juveniles, with a terminal cirrus; sheath strictly tubular, bearing scattered, brown or black, bulbous-based triangular, brittle spines, sometimes becoming bare, and scattered, thin, white, caducous indumentum; ocrea conspicuous, tightly sheathing, neatly horizontally truncate, lobed or somewhat saddle-shaped, armed as the sheath, spines often concentrated on ocrea margin; knee absent, although rounded horizontal swelling visible at the base of the leaf in some species; leaves sessile, or with a very short flattened petiole; rachis unarmed or sparsely to profusely armed on the underside; cirrus bearing reflexed acanthophylls; elaminate rachis co mmon on lower part of stems, bearing equidistant, alternate to opposite acanthophylls; spear leaf deep orange to bright crimson to light green; leaflets few to numerous, usually single-fold, sometimes with 2-4 folds, entire, acute, linear, lanceolate or sigmoid, regularly arranged, usually armed along the thickened margins with robust spines, less so distally, midribs evident, other large veins rather distant, transverse veinlets conspicuous, proximal few leaflets smaller than the rest, often erect, vertical to rachis and stiffly swept back across stem or arching and somewhat pendulous. Inflorescences produced in axils; peduncle enclosed within the leaf sheath and emerging from its mouth, hemisperical or flattened and rectangular in cross-section; prophyll tubular, tightly sheathing, 2-keeled, 2-lobed at its tip, much shorter than the sheath; peduncular bracts ca.4, ± distichous, tightly sheathing at first, later splitting longitudinally, each with a short triangular or straight lobe; rachis longer than the peduncle; rachis bracts like the peduncular, rather close; rachillae pendulous with a basal 2-keeled tubular prophyll and numerous distichous, short, tubular, somewhat inflated, striate bracts, each enclosing a flower cluster, eventually longitudinally splitting and tattering post anthesis; flower cluster partially covered by a tubular 2-keeled prophyll and consisting of 5, 7, 9 or 11 flowers arranged in a group; 1-3 pistillate flowers in the centre subtended by 2 lateral cincinni of 0-2 pistillate and 2-4 staminate flowers, each flower, apart from the central pistillate, bearing an open, spathulate, 2-keeled, prophyllar bracteole. Staminate flowers symmetrical; calyx membranous, striate basally, stalked, tubular, with 3, short, triangular, apiculate lobes; corolla enclosed or only slightly exceeding the calyx, divided almost to the base into 3, elongate, striate, valvate petals; stamens 6, filaments united to form a thick fleshy, androecial tube, free from the corolla, tipped with 6 shallow lobes, bearing pendulous, rounded, latrorse anthers on the inside; pollen elliptic, monosulcate, with scabrate, tectate exine; pistillode very narrow, conical, slightly exceeding the androecial tube. Pistillate flowers superficially very similar to the staminate except slightly broader; calyx and corolla similar; staminodial tube bearing tiny empty anthers; gynoecium tricarpellate, triovulate, ± ellipsoidal, covered in reflexed scales, style long, narrow, 3-angled; ovule basally attached, anatropous. Fruit ± spherical, stigmatic remains minute, conical; epicarp covered in vertical rows of rather thin reflexed scales, mesocarp very thin, almost obsolescent at maturity, endocarp not differentiated. Seed single, ± rounded, smooth or warty, basally attached with an oval hilum, covered with a thin, papery, sweet sarcotesta; endosperm homogenous, laterally penetrated by a smooth-margined mass of inner seed coat; embryo lateral opposite the intrusion. Germination adjacent-ligular; eophyll bifid, petiole of seedling dull reddish pink.
    Morphology
    Not studied.
    Biology
    Confined to lowlying tropical rain forest.
    Distribution
    Five species described from equatorial West Africa and the Congo Basin. Oncocalamus has a distinct Guineo-Congolian distribution and ranges from SE Nigeria to northern Angola, predominantly in coastal forest.
    Diagnostic
    Clustering high-climbing pinnate-leaved rattan palms of Equatorial West Africa; sheaths armed with detachable spines; pleonanthic and monoecious, the flowers are borne in paired cincinni within conspicuous bracts, the basal 1–few pistillate, the others staminate, an arrangement unique in the family.
    [PW]
    Use
    No local uses have been specifically recorded but the stems are probably used as a source of cane.

    Images

    Distribution

    Native to:

    Benin, Cabinda, Cameroon, Congo, Equatorial Guinea, Gabon, Nigeria, Zaïre

    Oncocalamus (G.Mann & H.Wendl.) H.Wendl. appears in other Kew resources:

    Date Reference Identified As Barcode Type Status
    Apr 30, 2002 Meijer [15255], Cameroon K000525829
    Dec 1, 2000 Norman [66], Zaïre K000525830
    Gossweiler [s.n.], Angola K000525841
    Gossweiler [7537], Angola K000520048
    Gossweiler [7537], Angola K000525842
    Dransfield, J. [JD7646], Cameroon 64774.000
    Sunderland, T.C.H. [1939], Cameroon 64055.000
    Sunderland, T.C.H. [1761], Cameroon 64210.000
    Sunderland, T.C.H. [1761], Cameroon 64211.000
    Sunderland, T.C.H. [1939], Cameroon 64225.000
    Sunderland, T.C.H. [1705], Cameroon 73529.000
    Sunderland, T.C.H. [1759], Cameroon K000114495
    Sunderland, T.C.H. [1871], Equatorial Guinea K000520047

    First published in O.C.E.de Kerchove de Denterghem, Palmiers: 252 (1878)

    Accepted by

    • Govaerts, R. & Dransfield, J. (2005). World Checklist of Palms: 1-223. The Board of Trustees of the Royal Botanic Gardens, Kew.

    Literature

    Palmweb - Palms of the World Online
    • T.C.H Sunderland, A taxonomic revision of the rattans of Africa (Arecaceae: Calamoideae) in Phytotaxa 51. 2012
    • J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008
    Flora of West Tropical Africa
    • F.T.A. 8: 110.
    • in Benth. & Hook. f.. Gen. Pl. 3: 881, 936 (1883)

    Sources

    Herbarium Catalogue Specimens
    'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.

    Kew Backbone Distributions
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Palmweb - Palms of the World Online
    Palmweb 2011. Palmweb: Palms of the World Online. Published on the internet http://www.palmweb.org. Accessed on 21/04/2013
    Content licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License http://creativecommons.org/licenses/by-nc-sa/3.0