Rhopaloblaste singaporensis (Becc.) Hook.f., Gen. Pl. 3: 892 (1883)

Primary tabs

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Malayapresent (World Checklist of Arecaceae)B
Restricted to Singapore and Peninsular Malaysia. In Malaysia, most frequent in Johore, but also recorded from Pahang and Perak in the Dindings and near Ipoh (Whitmore 1973; Dransfield, pers. comm.). (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Discussion

  • Rhopaloblaste singaporensis is extraordinary within the genus for many reasons. It is the only species of Rhopaloblaste that has clustering stems. The stem itself is slender, reaches up to than 5 m in height and bears no more than 8 leaves in the crown. The leaf possesses a distinctly elongate petiole; when the leaf dies, the petiole breaks leaving the sheath attached. The crownshaft is present and well defined, but is obscured by persistent, decaying leaf sheaths. The inflorescence, which typically bursts through the decaying leaf sheaths, is branched to just one order and the basal rachillae are not strongly recurved. The fruit-bearing rachillae are slender and bear small elliptic fruits. While these characters suggest that the species may be incorrectly placed in Rhopaloblaste, there are some striking similarities. For example, the leaf rachis with abundant grey-brown scales on the adaxial surface, the finely divided pinnate eophyll and the relatively large club-shaped embryo are characteristics of all species of Rhopaloblaste. Moreover, the inflorescence and fruit morphology of R. singaporensis can be interpreted as reduced forms of the larger structures found in all other species in the genus. The placement of R. singaporensis in the genus Rhopaloblaste has now been confirmed with molecular evidence (Norup 8& Baker, unpublished). The synonym Ptychoraphis longiflora is placed here following Moore (1970) and our own judgement that the trivial characters used to distinguish it from R. singaporensis (principally the long male flowers) do not fall outside the range of variation accepted for R. singaporensis in this account. Type material has not been found in Kew and is apparently not present in Singapore according to Whitmore (in Moore 1970), but we have ample evidence from the protologue to place this name in synonymy here. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Biology And Ecology

Conservation

  • Least concern. With its relatively wide distribution, R. singaporensis cannot be regarded as threatened at a global level under IUCN criteria. However, while some Malaysian populations occur in protected areas, the range of the species has certainly been reduced significantly. It is now very sparsely distributed in Singapore (Loo, pers. comm.) and the Perak populations are highly threatened (Saw, pers. comm.). (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Uses

Description

  • Small slender understorey clustering palm bearing 5 - 8 leaves per stem in the crown. Stem to 5 m tall, 1.9 -4 cm diam., surface greyish brown, leaf scars prominent; internodes 3 - 5 cm. Leaf sheath 20 - 35 cm long, with dense interlocking silvery white brownish scales on the surface, tubular, persistent after death of leaf; crownshaft present, but obscured by decaying leaf sheaths, 25 - 40 cm long, 2 - 3 cm diam.; petiole elongate, 60 - 70 cm long, moderately grooved on the adaxial surface, with sparse brownish membranous scales; rachis 1.7 - 1.8 m long, rounded, but moderately grooved on the adaxial surface, with dense grey-brown membranous scales; leaflets 42 - 50 each side of rachis, borne 2 - 2.5 cm apart, in one plane, spreading, middle leaflet 25 - 31 x 10 - 13 mm, narrowly linear, tapering acutely and bifid at the apex, discolorous, with greyish white ramenta present along the elevated mid-veins on the abaxial surface, twisted brownish black membranous scales on the adaxial surfaces of mid-veins, less dense on the abaxial, becoming more dense at the base of pinnae. Inflorescence 20 - 35 cm long, with a spread of 10 - 15 cm, emerging from the decaying leaf sheaths below the crownshaft, branched to 1 or 2 orders, primary branches 4 - 8, 20 - 30 cm long, basal pair of primary branches spreading at an angle approaching 90' to the primary axis of the rachis; prophyll 6 - 7 x 2 - 3 cm, greyish brown; peduncle 1 - 2 cm long, 0.5 - 1 cm diam., with blackish scales inside the very thin grooves on the rugose surface; rachillae very slender, 25 - 34 cm long, 1.4 - 3 mm diam., green, turning greenish brown with age. Staminate flower symmetric, 3.5 - 4.5 mm long, 1.5 - 2 mm diam.; sepals 1.3 - 1.5 x 1.9 - 2.1 mm, broad to rounded; petals 2.8 - 3 x 1.8 - 2 mm, linear- elliptic; stamens 2.7 - 3 mm long, filaments 1.4 - 1.5 mm long, connate at the base, anthers 1.4 - 1.5 mm long, 0.6 - 0.7 mm diam., yellowish brown; pistillode conical, 2.5 - 2.6 mm long, 0.9 - 1 mm diam. at the base. Pistillate flower 1.8 - 2 mm long, 2.8 - 3 mm diam.; sepals 1.7 - 2 x 2.4 - 2.5 mm, rounded; petals 2 - 2.5 x 1.8 - 2 mm, broadly obovate; staminodes 4, lobes 0.7 - 0.9 x 0.8 - 0.9 mm; gynoecium 1.6 - 1.7 mm long, 1.2 - 1.3 mm diam., ovoid. Fruit 10 - 12 mm long, 8 - 9 mm diam., ellipsoid, yellowish orange to red when mature; cupule of persistent perianth 2 - 3 mm long. Seed 6 - 7 mm long, 3.5 - 4 mm diam., ellipsoid, testa black. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Materials Examined

  • PENINSULAR MALAYSIA. Perak: Pangkor, July 1888, Curtis 1640 (K!); Dindings, 1900, Curtis 3443 (K!). Johore: Gunung Panti, June 1880, Kunstler 230 (K!); West Gunung Panti, July 1968, Dransfield 894 (K!); Bukit Petar, Sungai Endau, Sept. 1987, Gianno E153 (K!, KLU); Sungai Linggiu, Dam Site, July 1991, Saw et al. FRI 37418 (KEP, K!); Labis Forest Reserve, South Side Ridge, April 1966, Whitmore FRI 173 (KEP, K!); North of Labis, 5 miles, Nov. 1946, Henderson 38203 (B, BH, BO, K !, L, SING); Compt. 21, Gunung Arong Forest Research, May 1962, Meyer & Yong 94878 (KEP, K!); Datok Sarah, March 1973, Singh & Samsuri 1015 (KEP, K!, LAE!). SINGAPORE. Woodlands, March 1866, Beccari s.n. (FI!, type); In the wooded part of the Botanic Garden, Jan. 1878, Beccari s.n., April 1878, Beccari, s.n.; 1853, Lobb s.n. (K!); 1867, Maingay 1536 (K!); Oct. 1878, Murton 96 (K!); Bajan, 1892, Ridley s.n. (SING, K!); 1891, Ridley 3137 (SING, K!); Upper Pierce Reservoir, near Nee Soon Swamp Forest, Nov. 2002, Baker & Loo 1174 (K!, SING, SINU). CULTIVATED. Singapore Botanic Garden, Block A, Oct. 1915, Burkill s.n. (SING, K!); Royal Botanic Gardens, Kew, Palm House, May 1998, Anon. 1986-1000 (K!). (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A