Plectocomiopsis Becc., Fl. Brit. India 6: 479 (1893)

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Description

  • Moderate to robust, clustered, high-climbing, spiny, hapaxanthic, dioecious, rattan palms. Stem eventually becoming bare, often 3-angled, with long internodes and conspicuous nodal scars, basal branches borne in an axillary position. Leaves of mature climbing stems pinnate, cirrate; leaf sheath tubular, rather sparsely armed or unarmed, usually bearing caducous indumentum; knee absent; ocrea present, sometimes tattering, but usually remaining entire and conspicuous; flagellum absent; petiole present or absent, it and the proximal part of the rachis deeply channelled and sparsely spiny; cirrus and distal part of rachis abaxially armed with regularly arranged groups of reflexed grapnel spines; leaflets few to numerous, single-fold, lanceolate, entire, regularly arranged, sometimes armed along margins and/or midrib with conspicuous bristles and bands of caducous scales, midribs evident, transverse veinlets conspicuous. Inflorescences produced simultaneously from the axils of the most distal, often reduced leaves, branched to 2 (3) orders, inflorescence axis adnate to the proximal part of the internode above the subtending node, emerging from the leaf sheath mouth; peduncle short; prophyll tubular, 2-keeled, included within the leaf sheath; peduncular bracts absent (?always); rachis much longer than the peduncle; rachis bracts tubular, ± distichous, each subtending a horizontal or ± pendulous, first-order branch; first-order branches with basal, 2-keeled prophyll and close, distichous, tubular bracts with triangular limbs, each subtending a flower cluster (except in Plectocomiopsis corneri where inflorescences diffusely branched to 3 orders, and flowers borne on axes of all 3 orders); flower cluster monopodial, representing a condensed rachilla. Staminate flowers borne ± distichously in clusters of up to 32 flowers, each flower in the axil of a cup-like rachilla bract and bearing a cup-like, 2-keeled bracteole; calyx thick, very leathery, tubular, with 3 short lobes, the abaxial surface often covered in scale-like trichomes; corolla thick, leathery, tubular through most of its length, split distally to form 3 approximate triangular lobes, covered in scale-like trichomes; stamens 6, epipetalous, united laterally to form a tube tipped with 6 short, reflexed, free filaments bearing short, rounded to oblong, medifixed, introrse anthers; pistillode minute. Pollen ellipsoidal, bi-symmetric; apertures equatorially disulcate; ectexine tectate or semitectate, finely perforate rugulate, or reticulate, alternatively exine intectate with angular clavae interspersed with granulae, aperture margins similar to or slightly finer than surrounding ectexine; infratectum columellate; longest axis 19–34 µm [5/5]. Pistillate flowers rarely solitary, or borne in groups of 2–4 (rarely more), each in the axil of a cup-like rachilla bract and bearing a 2-keeled, cup-like bracteole and rarely a minute second bracteole; calyx tubular, thick, leathery, divided into 3 low lobes, frequently bearing scale-like trichomes, persisting into fruiting stage, enlarging, splitting and cracking irregularly; corolla thick, leathery, densely scaly, divided into 3 short lobes, later splitting irregularly; staminodial ring epipetalous, bearing 6 very short lobes and pendulous empty anthers; gynoecium ovoid to cylindrical, at anthesis scaly only near the base of the 3 apical stigmas, locules 3, incomplete, each with 1 anatropous, basally attached p vule. Fruit 1 (very rarely 2)-seeded, perianth whorls persistent and enlarging, stigmatic remains apical; epicarp covered in somewhat irregular vertical rows of reflexed scales, mesocarp thin, endocarp not differentiated. Seed basally attached, usually depressed, globose, sarcotesta thick, but not juicy, endosperm homogeneous; embryo basal. Germination adjacent-ligular; eophyll bifid, lamina composed of several folds. Cytology not studied. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)

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Bibliography

A. J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008
B. World Checklist of Arecaceae