Rhopaloblaste singaporensis (Becc.) Benth. & Hook.f.

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/38683/10137950

Conservation

LR/CD - conservation dependent

Banka, R., & Baker, W. (2004). A Monograph of the Genus Rhopaloblaste (Arecaceae). Kew Bulletin, 59(1), 47-60. doi:10.2307/4111073

Type

Singapore, Woodlands, March 1866, Beccari s.n. [Beccari Herbarium No. 1180, 1180A, 1180B] (holotype FI!).

Morphology General Habit

Small slender understorey clustering palm bearing 5 - 8 leaves per stem in the crown

Morphology Stem

Stem to 5 m tall, 1.9 -4 cm diam., surface greyish brown, leaf scars prominent; internodes 3 - 5 cm

Morphology Leaves

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

Morphology Reproductive morphology Inflorescences

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

Morphology Reproductive morphology Flowers

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

Morphology Reproductive morphology Fruits

Fruit 10 - 12 mm long, 8 - 9 mm diam., ellipsoid, yellowish orange to red when mature; cupule of persistent perianth 2 - 3 mm long

Morphology Reproductive morphology Seeds

Seed 6 - 7 mm long, 3.5 - 4 mm diam., ellipsoid, testa black.

Distribution

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.).

Ecology

In dipterocarp forest up to 180 m above sea level.

Vernacular

Kerinting (Bahasa Malaysia).

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.).

Note

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 & Baker, to be published).

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.).

Distribution

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.).

General 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.

Biology

In dipterocarp forest up to 180 m above sea level.

Vernacular

Kerinting (Bahasa Malaysia)

Use

Used for making spear handles and walking sticks. The fruits are sometimes eaten like Pinang (Areca catechu). Sometimes grown as an ornamental.