Scientific name

Arenga pinnata (Wurmb) Merrill

Synonyms

A. gamuto (Houtt.) Merr.; A. saccharifera Labill. Ex DC

Common names

Black sugar palm, areng palm, sugar palm

Family

Arecaceae

Origin

India, China, Myanmar, Thailand, Malaysia, Philippines

Naturalised distribution (global)

Locations within which Arenga pinnata is naturalised include parts of South-east Asia, some Pacific islands (Hawaii and Philippines) and parts of East Africa.

Introduced, naturalised or invasive in East Africa

Arenga pinnata is invasive in parts Tanzania (Tropical Biology Association 2010). The editors are not aware of records of the presence of this species in Kenya and Uganda, though this does not necessarily mean that it is absent from these countries.

Habitat

Forest gaps and edges and disturbed areas.

Description

Arenga pinnata is a medium-sized palm, growing to 20 m tall, with the trunk remaining covered by the rough old leaf bases. The trunk is 40-50 cm in diameter, and covered with black fibres and spines. The leaves are 6-12 m long and 1.5 m broad, simple pinnate (once-divided), with the pinnae in 1-6 rows, 40-70 cm long and 5 cm broad. A. pinnata flowers are yellow and showy. As most of the caryotas and arengas, after the tree finishes blooming, it dies. Flower stalk coming from among the leaves, much longer than the leaves (Riffle and Craft 2003). The fruit is purple. 4 cm in diameter. round to oval, containing generally 3 seeds, takes over one year to ripen.

Reproduction and dispersal

This species reproduces from animal-dispersed seed.

Economic and other uses

The sap is harvested for commercial use in southeast Asia, yielding a sugar known in India as gur, and is also fermented into vinegar and wine. The immature fruits are widely consumed in the Philippines and Indonesia and are made into canned fruits after boiling them in sugar syrup. The dark fibrous bark is manufactured into rope. This crop is a potential biofuel feedstock.

Environmental and other impacts

Arenga pinnata is capable of invading forest edges and can form dense stands that can inhibit the regeneration of native species. The raw juice and pulp are caustic.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Small plants can be uprooted and trees can be cut down as the palm cannot regenerate from cut stumps.

The editors could find no information on any biological control agents for this species.

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

References

Manuel Blanco, F. (1877-1883). Flora de Filipinas, según el sistema sexual de Linneo. Adicionada con el manuscrito inédito del. fr. Ignacio Mercado, las obras del fr. Antonio Llanos, y de un apéndice con todas las nuevas investigaciones botanicas referentes al archipiélago Filifino [sic]. Gran edicion., Manila: 1877-1883.

Uhl, N.W. and Dransfield, J. (1987). Genera Palmarum - A classification of palms based on the work of Harold E. Moore. Lawrence, Kansas: Allen Press.

Riffle, R. L. and Craft, P. (2003). An Encyclopedia of Cultivated Palms. Portland: Timber Press. Portland, Oregon.

Tropical Biology Association (2010). Usambara Invasive Plants - Amani Nature Reserve - www.tropical-biology.org/research/dip/species.htm.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: [email protected]