Ceratolobus concolor Blume, Rumphia 2: 165 (1843)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Borneopresent (World Checklist of Arecaceae)B
Sumaterapresent (World Checklist of Arecaceae)B
In lowland and hill mixed-Dipterocarp forests on hillslopes and valley bottoms, rarely on sandstone ridges, widespread in Borneo, very local in Sumatra; apparently frequently overlooked and rarely collected. (J. Dransfield, A monograph of Ceratolobus (Palmae). 1979)A

Discussion

  • Blume based this species on collections from Palembang, Sumatra, sent by Praetorius; he also mentions fronds collected by Korthals as belonging to the same species. A specimen with no collector or locality annotated and exactly corresponding to the plate in Rumphia of Ceratolobus concolor is present in Leiden, and this is assumed to be the type, collected by Praetorius. Plants of Ceratolobus with concolorous leaflets are found in Java, Sumatra and Borneo. Of these, one known from Java and one locality in Sumatra is abundantly distinct and is separated above as C. pseudoconcolor. Two problematic collections from South Sumatra are discussed above under this new species. Remaining populations of Ceratolobus with concolorous leaflets differ from each other in small degrees, the whole appearing as one variable taxon, which is here equated with C. concolor. Populations of C. concolor from Sabah (North Borneo) differ markedly from the type-yet there is a whole range of intermediates and in one instance even populations in one locality show a wide range of variation. Hence it has been impossible to distinguish satisfactorily any taxa within this complex, once C. pseudoconcolor has been removed. (J. Dransfield, A monograph of Ceratolobus (Palmae). 1979)A

Description

  • Slender clustering rattan up to 15 m tall, rarely more. Stems closely clustering by short suckers, to 5 mm diam. without sheaths, to 12 mm diam. with sheaths, internodes 12-25 cm long. Leaf sheaths pinky-grey-green when fresh and young, dull green when old and fresh, dull greeny-brown or brown when dry, covered in caducous scurfy grey indumentum and scattered chest- nut pseudoparenchymatous scales, and dark brown, easily-detached spiculate spines to 1 mm long, borne on pale yellowish-green bulbous bases, at least some of the spiculae grouped in horizontal partial whorls of four or more spiculae, the bulbous bases persistent long after the fall of the spiculae, in extreme instances the bulbous bases forming collar-like rings on the leaf sheaths; geniculus prominent, armed as is the sheath; ocrea very short to moderately conspicuous, to 5 mm long. Petiole very short (1 cm) to moderate (15 cm) (the type has almost no petiole) armed with scattered pale spines to 4 mm long, spiculae, pale indumentum, and dark brown scales, or sometimes scarcely armed at all; whole leaf to 1.25 m long including the cirrus to 40 cm long; rachis armed with grouped reflexed thorns up to 8 cm long, c. 6 cm distant, the distance decreasing above, the spine groups intergrading with the grapnel hooks on the cirrus above, these c. 1.5 cm distant, decreasing towards the tip. Leaflets in mature individuals 3-7 on each side of the rachis, usually 6, the lowermost pair usually somewhat smaller than the rest, occasionally very much smaller, 2-16 x 1-5 cm, the mid leaflets 15-21 x 6-8 cm, moderately plicate, dull green above, slightly paler below, without dense white indumentum, rhomboid, with a moderately well-defined apical portion 2-4 x 0.5 cm at the base, the leaflets alternate below, ± opposite above; lower margins unarmed, upper praemorse margins with scattered prickles; 15-25 main veins radiating from the base; transverse veinlets moderately prominent above and below. Emerging leaf pink. Inflorescences staminate and pistillate on separate plants, superficially similar, varying from erect with a very short peduncle, sometimes almost sessile, to pendulous on a peduncle to 20 cm long and 2-5 mm wide, rarely armed with very short (0.5 mm long) prickles; in forms with ? sessile inflorescences, inflorescence adnate to 8 cm above leaf sheath mouth on the next leaf sheath; in forms with pedunculate inflorescences, inflorescence scarcely adnate beyond leaf sheath mouth. Prophyll rather variable in size, 19-35 cm x 2.5-5 cm, wide (average about 26 x 4 cm) including the beak up to 3.5 x 0.3 cm flat with inrolled margins near the base, occasionally with scattered buff to chocolate- brown caducous indumentum on both adaxial and abaxial surfaces, pinkish-green when first emerging, later pale green and finally cinnamon-brown at anthesis. Axis branching to 2 orders with up to 8 first-order branches; first- order bracts tightly sheathing to 5 mm long. Staminate flower solitary, borne on an alveolus ± 1 mm diam., greeny-cream at anthesis; whole flower rather variable in size, 4.0-5.5 x 2-2.5 mm; calyx tubular, shallowly 3- lobed, c. 0.6 mm long, lobes bluntly triangular; corolla very shortly tubular, split for almost entire length into 3 petals, to 5.5 x 2.5 mm, gradually narrowed above to triangular tips; stamens 6, shortly epipetalous (c. 1.5 mm above base); filaments fleshy, triangular, laterally connate; anthers to 2.5 x 0.5 mm; pollen yellow; pistillode minute. Pistillate flower borne on an alveolus c. 1.5 mm diam. together with a sterile staminate flower, to 4.5 x 3 mm; calyx shallowly 3-lobed, up to 1 mm long; corolla tubular below, split to about I its length into 3 lobes c. 3 mm wide; staminodes borne about 1.5 mm above the bases of corolla-lobes, triangular-based narrowed to an apiculus c. 0.5 mm long; ovary c. 2.75 mm diam., rounded, tipped with the 3 twisted stigmas, each to c. 0.75 mm long. Sterile staminate flower superficially rather similar to the pistillate, to 3.5 x 2.5 mm; calyx to 1 mm long with 3 short lobes; corolla split almost to the base. Sterile flowers with filaments c. 0.75 mm long, borne about 0.75 mm above the base of the petals; empty anthers c. 15 x 0.2 mm; pistillode minute. Ripe fruit spherical or slightly ovoid, in the type c. 2 x 2 cm, in most material slightly less, up to 1l5 cm, tipped with the stigmatic remains, covered with 12 vertical rows of reflexed orangey-chestnut brown scales to 5 x 7 mm. Seed conforming to the pericarp with sarcotesta c. 2 mm thick. Diaspore to 1.4 x 0.9 cm in the type but usually less, somewhat flattened on one side. Endosperm rather deeply penetrated by dark brown ruminations. Embryo basal, c. 2 x 1 mm. Seedling with eophyll with four very slightly praemorse leaflets held in one plane in a fan. (J. Dransfield, A monograph of Ceratolobus (Palmae). 1979)A

Materials Examined

  • BORNEO. SARAWAK: Ulu Belaga, Rumah Nyaving, Dransfield & Manokaran 4676, (BH, K, SAR), 4695 (K, SAR) & 4703 (K, SAR). SABAH: without locality, 1877-78, Burbridge s.n. (K). Keningau, Apin- apin, Puasa-Angian 3879 (K) & 36656 (SING). Marotai, Maidin 3684 (K). KALIMANTAN: Kalimantan Selatan, Muara Uya, Jaro, Dransfield 2074 (BO, K, L), 2115 (BO, K, L), 2181 (cult. in Hort. Bogor.) & 2223 (BO). Barabai, Kiu, Meratus Mts, Dransfield 2814 (BO, K, L) & 2819 (BO). Kalimantan Timur: Balikpapan, Kenangan, Dransfield 4352 (BO, K, L), 4389 (BO), 4404 (BO, K) & 4452 (BO). Tarakan, Nunukan near Sg Binusan, Meijer 2434 (BO). SUMATRA. West Sumatra: Batang Singalang, Korthals s.n. (L). Padang, Air Mancur, Beccari P.S. 525 (FI, K). Talakmau, Bunnemeijer 562 (BO); Tapan, km 39 Sg Penuh-Tapan, Dransfield & Mogea 4160 (BO, K, L). Lampung: Forbes 1561 (K). No locality (but assumed to be Palembang) Praetorius s.n. (holotype L). (J. Dransfield, A monograph of Ceratolobus (Palmae). 1979)A