Pometia pinnata

Common name: Fijian longan

Other common names: Island lychee, Oceanic lychee, Taun

Names in non-English languages: Philippines

Description

A tropical relative of the Litchi (Litchi chinensis), this fruit tree originates from the geographic region extending from southern India, through Sri Lanka, Southeast Asia and Melanesia to Polynesia in the Western Pacific.

It is a tall tree in closely spaced forests, reaching heights of up to 35 m (115 ft) or more with a straight, round trunk up to 90 cm (3 ft) in diameter and with buttressed roots on older trees. On open sites it is more commonly 15 to 20 m (50 to 65 ft) tall with a short, low-branching trunk supporting a rounded crown. The bark is smooth, grey to orange-brown and lightly flaking, leaving a mottled surface.

The leaves are large, up to 1 m (3 ft) long and compound, made up of pairs of leathery, green leaflets with wavy margins. They pink to red when they emerge, becoming green with age.

Flowering appears to follow the rains, the timing and frequency of which varies by region. In areas with two rainy season events a year, flowering follows each event and in areas with perpetually wet conditions flowering is usually intermittent to continuous.

The flowers are green-white, small and insignificant, blooming in mixed clusters of female and male flowers on the same tree. They are followed by small egg-shaped fruit, up to 3 cm (1 in) long in large bunches similar to Litchi. Natural variation is noticeable in the fruit which, depending on the variety may be yellow, red or dark purple when ripe.

Use

The thick shell of the ripe fruit is cracked and peeled away to access the sweet, juicy translucent pulp, which surrounds a single seed. The pulp is described as having a taste and texture similar to Longan (Dimocarpus longan), another Litchi relative. The oily seed is sometimes boiled or roasted and eaten as a nut, but is barely edible.

It is considered a minor timber tree, due in part to its often poorly formed trunk. The  wood is medium-weight, around 580 to 720 kilograms per cubic meter and has medium to high natural resistance to decay. This puts it in the durable hardwood class suitable for indoor and outdoor construction.

The sawn timber is used mostly in light construction, indoor joinery work and for making furniture and cabinets. The roundwood is cut for turnery, making into tool handles as well as for firewood. 

Work is needed to identify, select and propagate trees with the most desirable fruit and timber characteristics.

Climate

Grows naturally in humid to very humid tropical lowland climates, generally in areas with annual lows of 19 to 25 °C, annual highs of 27 to 35 °C, annual rainfall of 1500 to 5000 mm and a dry season of 4 months or less. Fijian Longan trees may fail to thrive in areas where the average low of the coldest month is below 14 °C (57 °F).

Growing

New plants are commonly grown from seed or stem-cuttings. It performs best on free-draining clay, loam or sand soils of a moderately acid to alkaline nature, generally with a pH of 5.0 to 8.0 and on sites with full to partial sun exposure. It is intolerant of salt spray and soil salt conditions.

Problem features

It is listed as a weed in a least one reference publication, but without any declared or serious weed status. In its native range birds and bats eat the fruit and disperse the seed.

The dust from sawn timber can be an irritant to the respiratory tract.

Where it will grow

With irrigation or groundwater

References

Books

  • Ashton, M.S. 1997, A field guide to the common trees and shrubs of Sri Lanka, Wildlife Heritage Trust of Sri Lanka, WHT Publications (Pvt.) Ltd., Colombo

  • Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

  • Elevitch, C. R & Wilkinson, K. M. 2000, Agroforestry Guides for Pacific Islands, 1st ed., Permanent Agriculture Resources, Holualoa, Hawaii

  • Elevitch, C. R. 2006, Traditional trees of Pacific Islands: their culture, environment and use, 1st edition, Permanent Agriculture Resources, Hōlualoa, Hawaii

  • Food and Agriculture Organization of the United Nations (FAO) 1984, Food and Fruit-bearing Forest Species, 2 : Examples from Southeastern Asia, FAO Forestry Paper no 44/2, Rome

  • Kukachka, B. F & Forest Products Laboratory (U.S.) 1970, Properties of imported tropical woods, United States, Department of Agriculture, Forest Service, forest Products Laboratory, Madison

  • Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

  • Martin, F. M., et al. 1987, Perennial edible fruits of the tropics : an inventory, U.S. Dept. of Agriculture (USDA), Agricultural Research Service, U.S. Government Printing Office (GPO), Washington, D.C.

  • Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

  • Reyes, G. 1992, Wood densities of tropical tree species, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans, Louisiana

  • Scheffer, T. C & Morrell, J. J. 1998, Natural durability of wood : a worldwide checklist of species, Forest Research Laboratory, Oregon State University, Corvallis, Oregon

  • Walter, Annie & Ferrar, P. (Paul) & Sam, Chanel & Australian Centre for International Agricultural Research & Institut de recherche pour le développement 2002, Fruits of Oceania, ACIAR/IRD Editions, Canberra

  • Wickens, G. E 1995, Edible nuts, Food and Agriculture Organization of the United Nations (FAO), Rome

Articles, Journals, Reports and Working Papers

  • Watson, B.J., & Moncur, M. 1985, Guideline criteria for determining survival, commercial and best mean minimum July temperatures for various tropical fruit in Australia (Southern Hemisphere), Department of Primary Industries Queensland (DPI QLD), Wet Tropics Regional Publication, Queensland

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