Pogonotium J.Dransf., Kew Bull. 34: 763 (1980)

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Number of Taxa

  • 3 species

Discussion

Biology And Ecology

  • In Borneo, all three species occur as small populations confined to podsolised soils on ridgetops at about 700–1000 m altitude (at the transition between lowland and montane forest) or to some facies of ‘kerangas’ forest (heath forest). In the Malay Peninsula, Pogonotium ursinum has been found in lowland dipterocarp forest. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Etymology

Diagnosis

Description

  • Solitary or clustered, spiny, erect or short-climbing, pleonanthic, dioecious, rattan palms. Stem with short internodes. Leaves pinnate, without cirrus; sheath tubular, densely armed with whorled and scattered spines and caducous tomentum, terminating in 2 erect, narrow auricles, 1 on each side of the petiole, the auricles variously armed like the sheath; knee absent or poorly developed; flagellum absent; petiole well developed, flat adaxially, rounded abaxially, armed with reflexed grapnel spines and various papillae and hairs; rachis armed as the petiole; leaflets few to very numerous, linear, single-fold, regularly arranged, very crowded to very distant, the surface covered with a variety of bristles and scales, midribs prominent adaxially, transverse veinlets short, conspicuous. Inflorescences axillary but adnate to the internode and leaf sheath of the following leaf, held erect between the 2 auricles of the subtending leaf, ± sessile, the pistillate branching to 2 orders, the staminate to 3 orders; prophyll enclosing the inflorescence, boat-shaped, with a flattened beak, armed or unarmed, splitting longitudinally along the mid adaxial or abaxial line, thus exposing the flowers; rachis bracts very much smaller than the prophyll, with free tips, each and the prophyll subtending a variously hairy branch; bracts on first-order branches tubular at the base, with triangular limbs. Staminate flowers solitary, borne subdistichously on branches of the second or third-order, each subtended by a minute, short, tubular, triangular bract and bearing a 2-keeled bracteole; calyx tubular in proximal part, striate, with 3 triangular lobes; corolla split almost to the base into 3 triangular valvate lobes; stamens 6, borne at the base of the corolla lobes, filaments fleshy, elongate, inflexed at the tips, anthers oblong, medifixed, sagittate basally, latrorse; pistillode minute. Pollen spheroidal, bi-symmetric; monoporate with pore on one of two short axes of grain; ectexine tectate or semi-tectate, perforate-rugulate or foveolate-reticulate, aperture margin usually similar; infratectum columellate; longest axis 18–32 µm [2/3]. Pistillate flowers in dyads, each subtended by a small, triangular bract, and consisting of a pistillate and a sterile staminate flower and two 2-keeled cup-like bracteoles. Sterile staminate flower like the fertile but tending to be contorted by close-packing and with empty flattened anthers and a variable pistillode. Pistillate flowers larger than the staminate; calyx cupular, striate, lobes triangular, valvate; corolla split almost to the base into 3 triangular, valvate lobes; staminodes 6, epipetalous; gynoecium incompletely trilocular, triovulate, ovoid, scaly, stigmas 3, fleshy, rugose, divergent, ovule basally attached, anatropous. Fruit 1-seeded, globose or ovoid, beaked, stigmatic remains apical; epicarp covered in neat vertical rows of reflexed magenta to chestnut-coloured scales, mesocarp becoming thin and dry at maturity, endocarp not differentiated. Seed basally attached, sarcotesta thick, sweet, endosperm homogeneous; embryo basal. Germination adjacent-ligular; eophyll pinnate or with a single pair of divergent leaflets. Cytology not studied. (J. Dransfield, N. Uhl, C. Asmussen, W.J. Baker, M. Harley and C. Lewis. 2008)

Relationships

Uses

Bibliography

  • Dransfield, J. , Uhl, N. , Asmussen, C. , Baker, W.J. , Harley, M. & Lewis, C. 2008. Genera Palmarum. The evolution and classification of palms. Kew Publishing, Royal Botanic Gardens Kew.