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<taxonx xmlns:dc="http://digir.net/schema/conceptual/darwin/core/2.0" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<taxonxHeader>

<mods:mods>

<mods:titleInfo><mods:title>Genera Palmarum. The evolution and classification of palms</mods:title></mods:titleInfo>

<mods:name>

<mods:namePart type="family">Dransfield</mods:namePart>

<mods:namePart type="given">J.</mods:namePart>

<mods:namePart type="family">Uhl</mods:namePart>

<mods:namePart type="given">N.</mods:namePart>

<mods:namePart type="family">Asmussen</mods:namePart>

<mods:namePart type="given">C.</mods:namePart>

<mods:namePart type="family">Baker</mods:namePart>

<mods:namePart type="given">W.J.</mods:namePart>

<mods:namePart type="family">Harley</mods:namePart>

<mods:namePart type="given">M.</mods:namePart>

<mods:namePart type="family">Lewis</mods:namePart>

<mods:namePart type="given">C.</mods:namePart>

</mods:name>

<mods:originInfo>

<mods:dateIssued>2008</mods:dateIssued><mods:publisher>Kew Publishing, Royal Botanic Gardens Kew</mods:publisher></mods:originInfo>

</mods:mods>

</taxonxHeader>

<taxonxBody>

<treatment rank="genus">

<div type="diagnosis"><p>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.</p></div>

<nomenclature>

<name>Oncocalamus</name>

<author>(G. Mann and H. Wendl.) G. Mann and H.Wendl. ex Hook.f. in Benth. and Hook.f.</author> 

<citation>Gen. Pl. 3: 881, 936 (1883).</citation>

<type>Type; Oncocalamus mannii; (H.Wendl.) H.Wendl.</type>

<synonymy>

<name>Calamus subgenus Oncocalamus</name>

<author>G. Mann and H. Wendl.</author>

<bibref>G. Mann and H. Wendl., Trans. Linn. Soc. London 24: 436 (1864).</bibref>

</synonymy>

</nomenclature>

<div type="etymology"><p>Onkos — hook, calamus — reed, but no explanation was given for the derivation.</p></div>

<div type="description"><p>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.</p></div>

<div type="distribution"><p>Five species described from equatorial West Africa and  the Congo Basin.</p></div>

<div type="anatomy"><p>Not studied.</p></div>

<div type="relationships"><p>The monophyly of Oncocalamus has not been tested. The genus resolves as sister to a clade of Eremospatha and Laccosperma with moderate  support (Baker et al. 2000a, 2000b, Asmussen et al. 2006).</p></div>

<div type="uses"><p>No local uses have been specifically recorded but the stems are probably used as a source of cane.</p></div>

<div type="taxonomic accounts"><p>Sunderland (2001, 2007).</p></div>

<div type="fossil record"><p>No generic records found.</p></div>

<div type="discussion"><p>The strange flower cluster of Oncocalamus is unique, not only in the subfamily but within the whole family. Vegetatively, Oncocalamus is very similar to Eremospatha and Laccosperma.</p></div>

<div type="vernacular"><p>Common names numerous (Sunderland 2001). </p></div>

<div type="biology_ecology"><p>confined to lowlying tropical rain forest.</p></div>

<div type="conservation"><p></p></div>

</treatment>

</taxonxBody>

</taxonx>