Korthalsia robusta Blume

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident

Shahimi, S., Conejero, M., Prychid, C.J. et al. (2019). A taxonomic revision of the myrmecophilous species of the rattan genus Korthalsia (Arecaceae). Kew Bulletin 74: 69. https://doi.org/10.1007/s12225-019-9854-x

Type

Indonesia, Sumatra, Praetorius s.n. (holotype L: isotype K!, L!).

Morphology General Habit

Robust, clustering rattan climbing to 40 m

Morphology Stem

Stem with sheaths 20 – 35 mm diam., without sheaths 14 – 20 mm diam.; internodes 24 – 25 cm

Morphology Leaves

Leaf 1.5 – 3.0 m long including cirrus and petiole; sheath bright green to green, with abundant dark brown to brown-black floccose, sparsely armed with scattered black, triangular spines, spines 2 – 30 mm long, 1 – 2 mm wide; ocrea 16.0 – 41.0 × 3.0 – 7.0 cm, conspicuous, diverging from the angle at stem just above the petiole, the margins tending to inroll, papery, brown in colour, armed with abundant 2 – 30 mm long dark brown spines, black ants usually abundant and very noisy; cirrus 0.50 – 1.75 m, armed with recurved grapnel spines organised in whorls; petiole 10 – 35 cm, 12 – 30 mm wide and 4 – 6 mm thick at base, flattened adaxially, abaxially rounded, with slightly grey indumentum, sparsely armed with spines as sheath; rachis 0.65 – 1.35 m, armed with recurved grapnel spines; 6 – 10 leaflets each side of rachis, regularly arranged, rhomboid to broadly rhomboid, mid-leaf leaflets 20.2 – 27.8 × 4.2 – 13.8 cm, leaflet dull green to dark green above, glabrous, with grey-whitish indumentum under surface, distal margin conspicuously praemorse, transverse veinlets conspicuous, fine and closely spaced c. 0.5 mm

Morphology Reproductive morphology Inflorescences

Inflorescence congested, 34.9 – 51.0 cm long including 3.5 – 15.0 cm peduncle, branched to 2 orders; prophyll 2.5 – 8.0 × 2.2 – 3.7 cm, with caducous, brown indumentum; rachis bracts up to 12.3 – 16.2 × 4.7 – 8.0 cm, conspicuous, inflated, with caducous, dark brown indumentum and black spicules; primary branches 3, 3.0 – 4.5 cm apart; proximal primary branch 16.0 – 17.0 cm long, with up to 2 rachillae; rachillae 13.0 – 16.0 cm long and slender, stalk not visible, 1.2 – 2.0 cm wide, lacking hairs between rachilla bracts

Morphology Reproductive morphology Flowers

Flower 8.4 – 11.0 × 3.4 – 5.0 mm in the bud

Morphology Reproductive morphology Fruits

Fruit round to oblong, 1.8 – 2.3 × 0.9 – 1.6 cm covered in 16 – 18 vertical rows of mid-brown scales with straw-coloured margins

Morphology Reproductive morphology Seeds

Seed 1.8 × 1.0 cm; endosperm homogeneous

Distribution

Borneo (Sabah, Sarawak, Central, East and South Kalimantan), Philippines (Palawan), Sumatra

Ecology

Lowland dipterocarp forest.

Vernacular

Oros (Kutai dialect), Rotan lasas (Kadazan), Wi semut (Iban), Wae asa (Kelabit language), Wae perah (Penan), Ayas (Pasir language).

Note

Korthalsia robusta is similar to K. hispida but can be easily distinguished from K. hispida by the absence of black spicules on the sheaths, ocreas, and bracts, and by the very congested inflorescences. Korthalsia robusta is a noisy rattan and inhabited by ants of the genus Camponotus (Mattes et al. 1998).

Use

Stem used for tying and weaving of baskets, shoots edible, handicraft and construction.