Retispatha dumetosa J.Dransf., Kew Bull. 34: 531 (1980)

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Distribution

Map uses TDWG level 3 distributions (https://github.com/tdwg/wgsrpd)
Borneo present (World Checklist of Arecaceae)B
Known from two collections. Elsewhere in Sarawak, Kalimantan and Sabah; endemic to Borneo. (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Discussion

  • An infrequent rattan, found in damp hollows on hill slopes and beside small streams in lowland and hill dipterocarp forest on Belait formation sandstones and Setap Shales at altitudes up to 350 m, elsewhere in Borneo occurring up to 700 m. Although known in Brunei from just two collections, we have observed it in several other localities.
    Although Retispatha is found throughout Borneo, it is always very local. It is likely to be passed over as juveniles of other rattans, although once known, it is unmistakable. The habit, complete lack of cirrus and flagellum, the lack of a knee and the black spine whorls on the leaf sheaths are useful diagnostic vegetative characters. The inflorescences with their net-like bracts are unlike those of any other rattan. Populations growing in the 1st Division of Sarawak differ slightly from typical R. dumetosa in the more slender stems and in the smaller male flowers which are exposed rather than hidden by bracts. Although three collections have been made in the 1st Division, they are all of male plants. It is possible that when female plants are found, the 1st Division populations may turn out to be specifically distinct from R. dumetosa. In Brunei R. dumetosa is particularly tall and robust and has been found reaching to the forest canopy, heights not recorded elsewhere in Borneo.
    Bukit Belalong, Sungei Belalong and Kuala Belalong are named after this unusual rattan species, that occurs in some abundance on the east bank of the Sungei Temburong just downstream from Kuala Belalong and, more rarely on Bukit Belalong itself. It is not infrequent in Belait and Tutong Districts in the headwaters of the major rivers. (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Etymology

  • Forming thickets (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Common Name

  • Uwai Belalong (Dus.) (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Uses

  • None known; the cane is very solid and heavy. (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Description

  • Robust thicket-forming dioecious, pleonanthic rattan with short massive stems, rarely exceeding 8 m long, but in Brunei to 15 m or more; stem without sheaths to 7 cm diam., with to 10 cm diam., usually less; bare stem dark green with short internodes to 10 cm and conspicuous nodes, also sometimes with bulbil shoots and adventitious roots. Sheaths without knee, dull green, densely armed with black flattened spines of length varying from 1.5-60 mm, the larger with paler bases and arranged in oblique partly reflexed combs, pale brown tomentum also abundant; ocrea conspicuous on emerging sheaths, soon disintegrating. Leaf curved, ecirrate, to almost 4 m long; petiole to 60 cm, conspicuously channelled and armed with lateral spine groups; leaflets c. 80 on each side of the rachis, very regular, dark green, armed with black bristles along the margins and lower surface of the main vein. Inflorescence male and female superficially similar, pendulous to c. 1 m with few branches; main axis and branches covered in tubular net-like bracts, pale straw-coloured, the main bracts also armed with black spine whorls; ultimate bracts to 8 cm long, distichous and imbricate, each enclosing a short catkin-like flower-bearing branch. Fruit developing inside the net-like bracts, the nets expanding to accommodate the enlarging fruit; fruit ovoid to obpyriform to 20 × 18 mm, bright green with brown scale margins, ripening to yellowish-brown with darker margins. Seed solitary, obscurely angled; sarcotesta sweet; endosperm homogenous. Seedling leaf pinnate with ciliate hairy leaflets. (Figs. 76-78, Pl. 15A, 15B) (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Materials Examined

  • BEL: Melilas, Bt.Batu Patam, Dransfield J. 6602.TEM: Amo, K. Belalong, Dransfield J. 7073. (Dransfield, J. 1997: The Rattans of Brunei Darussalam)A

Bibliography

    A. Dransfield, J. 1997: The Rattans of Brunei Darussalam
    B. World Checklist of Arecaceae