Korthalsia (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Korthalsia Blume

Protologue: Rumphia 2: 166 (1843).

Family: Palmae

Chromosome number: 2n= 32 (Korthalsia laciniosa, K. rostrata)

Korthalsia cheb Becc., Malesia 2: 67 (1884);

Korthalsia echinometra Becc., Malesia 2: 66 (1884);

Korthalsia flagellaris Miq., J. Bot. Néerl. 15 (1861);

Korthalsia laciniosa Griff. ex Mart., Hist. Nat. Palm. 3 (2nd ed.): 211 (1845), synonym: Korthalsia grandis Ridley (1902);

Korthalsia rigida Blume, Rumphia 2: 167 (1843);

Korthalsia robusta Blume, Rumphia 2: 170 (1843), synonym: Korthalsia macrocarpa Becc. (1918);

Korthalsia rostrata Blume, Rumphia 2: 168 (1843), synonym: Korthalsia scaphigera Griff. ex Mart. (1845).

• Korthalsia spp. (in general, in trade): Malaysia: rotan merah.

Korthalsia cheb : Malaysia: keb, wee jematang tengan.

Korthalsia echinometra : Indonesia: uwi hurang, rotan meiya

• Malaysia: rotan dahan, rotan semut, rotan udang.

Korthalsia flagellaris : Malaysia: rotan dahan.

Korthalsia laciniosa : Malaysia: rotan dahan.

Korthalsia rigida : Malaysia: rotan dahan.

Korthalsia robusta : Malaysia: rotan asas, lasas.

Korthalsia rostrata : Malaysia: rotan semut, rotan udang.

Korthalsia is a genus of about 26 species, widely distributed in SouthEast Asia from Burma and the Andaman and Nicobar Islands, IndoChina southwards and eastwards to New Guinea with greatest diversity in Sumatra, Peninsular Malaysia and Borneo.

Korthalsia cheb is endemic to Borneo where it is widespread but nowhere common. It is occasionally cultivated near longhouses in Sarawak.

Korthalisa echinometra is a conspicuous and abundant rattan in Sumatra, Peninsular Malaysia and Borneo; it is occasionally cultivated near longhouses in Sarawak.

Korthalsia flagellaris is widespread in Peninsular Malaysia, southern Thailand, Sumatra and Borneo where it occurs exclusively in lowland peatswamp forest.

Korthalsia laciniosa is one of the most widespread species, occurring from IndoChina and the Andaman and Nicobar Islands to Peninsular Malaysia, Sumatra and Java, and the Philippines, but not Borneo.

Korthalsia rigida is widespread occurring from southern Thailand and Peninsular Malaysia to Borneo, Sumatra and Palawan.

Korthalsia robusta is confined to Sumatra, Borneo and Palawan.

The most important use of Korthalsia species is as a source of very durable cane for weaving strong baskets. Some species such as K. echinometra are highly sought after for their canes because they are a preferred constituent of particular types of baskets. Occasionally, because of the dull reddish colour they are used mixed with canes of contrasting colour such as those of Calamus caesius Blume. In addition to their use in basketry, canes of Korthalsia spp. are incorporated into cheap furniture, some of which is exported and they are widely used for cordage, particularly in situations demanding great durability.

The fruit of some species is eaten but there is little flesh.

Cane diameter varies from very slender (6 mm) to moderately robust (40 mm or more). Internode length varies from about 10 cm to over 40 cm. The cane surface is dull and reddishbrown and its internal structure shows great evenness of texture. The inner epidermis of the leafsheaths is not easily separable from the cane surface and the nodes are frequently scarred on one side by the remains of axillary buds or branches. These factors detract from the overall marketability of the canes, which are otherwise very durable and not unattractive.

• Slender to moderately robust, high-climbing, hapaxanthic, hermaphroditic rattans, usually densely clustering and also frequently branching high in the canopy to produce large aerial entanglements.
• Leaf varying from scarcely 40 cm to more than 3 m long; leafsheath lacking a knee and always terminating in an ocrea; the leafsheath and ocrea variously armed with sparse to dense spines; ocrea tightly sheathing, loosely expanded and netlike, greatly swollen and antinfested or diverging from the sheathed stem with margins inrolled and antinfested; petiole absent to welldeveloped; cirrus welldeveloped; leaflets usually rather few in number, lanceolate to diamondshaped with the upper margins jagged (praemorse), leaflet undersurface often covered with indumentum and leafbase stalked.
• Inflorescences produced simultaneously from the topmost nodes, branching to 3 orders, death of the stem following flowering and fruiting; rachillae cylindrical, usually densely tomentose, the flowers embedded in the tomentum.
• Fruit spherical to ovoid, covered with vertical rows of flat scales with fimbriate margins; mesocarp fleshy; sarcotesta absent; endosperm homogenous or ruminate.
• Seedlingleaf bifid or entire.

Korthalsia cheb : stem without leafsheaths c. 20 mm in diameter, with sheaths 30 mm in diameter; ocrea to 25 cm×4.5 cm, inflated, usually filled with ants. Leaflets diamondshaped.

Korthalsia echinometra : stem without leafsheaths to 20 mm in diameter, with sheaths to 30 mm in diameter; ocrea to 10 cm×5 cm, very spiny, inflated and filled with ants. Leaflets lanceolate.

Korthalsia flagellaris : stem without leafsheaths to 25 mm or more in diameter, with sheaths to 40 mm or more; ocrea tightly sheathing, tattering with age. Leaflets lanceolate with conspicuous long stalks, rusty indumentose on the undersurface.

Korthalsia laciniosa : stem without leafsheaths to 35 mm in diameter, with sheaths to 40 mm or more; ocrea netlike, tightly sheathing, spiny. Leaflets diamondshaped.

Korthalsia rigida : very variable. Stem without leafsheaths 620 mm in diameter, with sheaths to 30 mm in diameter; ocrea usually short, tightly sheathing, sometimes tattering, very sparsely spiny. Leaflets diamondshaped.

Korthalsia robusta : stem without leafsheaths to 25 mm in diameter, with sheaths to 35 mm in diameter; ocrea elongate, to 25 cm long, diverging from the sheathed stem, spiny, the margins inrolling to form a chamber, usually occupied by ants. Leaflets diamondshaped.

Korthalsia rostrata : stem without leafsheaths 69 mm in diameter, with sheaths 815 mm in diameter; ocrea rounded, to 4 cm long, inflated and usually antinfested. Leaflets diamondshaped.

There is little information on growth and development. Clustering and aerial branching behaviour is unusual in this genus and would repay further study. It is not known whether aerial branch production is in any way related to the onset of flowering and hence termination of individual stem growth.

Many species of Korthalsia have close association with ants that make their nests within the swollen ocreas. The antrattan relationship also seems to involve the presence of scale insects that are husbanded by the ants for honey dew on young rattan tissue. Ants occupying the ocreas of some species are extremely aggressive and in K. robusta and K. hispida Becc. are also noisy, producing an alarm call when disturbed by banging their mandibles against the dry ocreas.

Most species of Korthalsia are widespread and quite tolerant of disturbance, often being the most well represented rattan genus in loggedover forest. This wide dispersal may be correlated with the hapaxanthic behaviour of production of large numbers of fruit simultaneously. K. flagellaris is confined to peatswamp forest; K. concolor Burret is restricted to forest developed on ultramafic rock in Sabah. Most species occur in the lowlands, but K. laciniosa has been recorded as high as 1100 m above sealevel in Peninsular Malaysia.

Propagation is from seed. Only K. cheb and K. echinometra have been recorded as being cultivated by villagers, on a small scale, in western Sarawak. Supplies from the wild seem otherwise to be sufficient for local basketmaking throughout much of the range of the genus. Harvesting is similar to harvesting of other similarsized species.

Several species are cultivated in botanical gardens and arboreta throughout the SouthEast Asian region.

As there is great demand for the canes of Korthalsia spp. for local basketmaking, it seems likely that local cultivation may continue and perhaps expand, especially where the wild resource is in short supply. It is unlikely, however, that there will ever be any commercial planting of these rather poor quality canes, no matter how durable and sought after they may be at the village level.

• Dransfield, J., 1979. A manual of the rattans of the Malay Peninsula. Malayan Forest Records No 29. Forest Department, Kuala Lumpur. pp. 3754.
• Dransfield, J., 1981. A synopsis of Korthalsia (PalmaeLepidocaryoidae). Kew Bulletin 36: 163194.
• Dransfield, J., 1984. The rattans of Sabah. Sabah Forest Records No 13. Forest Department, Sabah, Malaysia. pp. 1333.
• Wan Razali Wan Mohd, Dransfield, J., & Manokaran, N. (Editors), 1992. A guide to the cultivation of rattans. Malayan Forest Records No 35. Forest Department, Kuala Lumpur. p. 53.

J. Dransfield & J.P. Mogea

3 Minor rattans