Common name: Limeberry

Limeberry is an ornamental and fruiting shrub originating in Southeast Asia, its natural range extending across parts of southern China, Vietnam, Thailand, Malaysia and the Philippines.

It has a multi-stemmed, wide-branching habit and reaches heights of up to 7 m (23 ft), though it is more typically 2 to 3 m (7 to 10 ft) tall and grows at a slow to moderate rate, depending on the growing conditions. The branches are armed with sharp needle-like spines up to 1.6 cm (0.6 in) long, arising in pairs from the base of the leaves. 

The leaves are trifoliate, consisting of three dark glossy green oval leaflets and with the middle leaflet up to 4 cm (1.6 in) long and twice the size of the other two. They have a resinous, citrusy aroma when crushed and remain on the plant in all seasons.

The flowers are small, three-petaled, white and sweetly fragrant, with a scent of orange blossoms. They bloom on and off throughout the year, though they are most abundant in summer. 

Fertilised flowers develop into are small oval fruit up to 1.5 cm (0.6 in) long with thick, dimpled green peel, becoming red to purple-red when ripe. The pulp is jelly-like, bitter-sweet, with a citrus marmalade flavour and surrounds a single seed, though occasionally two or three seed. 

Use

The fruit are edible but too bitter and astringent to be eaten fresh and are either preserved in syrup, candied and dried, made into jam or marmalade, or into a fruit syrup or cordial. They are also commonly made into pickles in southern and western India.

Its low branching habit, deep green foliage, fragrant flowers and sharp spines have led to its cultivation as a garden hedge and barrier plant. Its small leaves also make it a suitable candidate for bonsai culture.

The stem wood, although small in diameter, is hard and durable. It is reportedly used for making tool handles and also makes an excellent firewood and charcoal.

Climate

Grows naturally in moderately humid subtropical and tropical lowland to mid-elevation climates, generally in frost-free areas with annual lows of 16 to 25°C, annual highs of 25 to 35°C, annual rainfall of 600 to 2000 mm and a dry season of 8 months or less.

Growing

New plants are usually raised from seed, though cuttings are an alternative. Performs best on rich, free-draining clay, loam and 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 has poor tolerance to slow-draining or waterlogged soils.

Problem features

Birds eat the fruit and disperse the seed. Once established, it re-seeds naturally, forming dense thickets.

It is recorded as an invasive species on the island of Reunion in the Indian Ocean and in the eastern Caribbean on the islands of Guadeloupe, Martinique and St Martin. It also suckers freely from the roots, which contributes to its weediness. The Hawaii Pacific Weed Risk Assessment project (HPWRA) assessed it as a high weed risk species for Hawaii. 

The branches are armed with sharp spines that can inflict injury on the unwary.

Books

• Adams, C. D. 1972, Flowering plants of Jamaica, University of the West Indies, Mona, Greater Kingston

• Bannochie, Iris, 1993. Gardening in the Caribbean. 1 Edition. Macmillan.

• Brown, William Henry. 1920, Minor products of Philippine forests, Bureau of Printing, Manila

• Chaplin, L. T. & Brandies M. M. 1998, The Florida Gardener's Book of Lists, Taylor Publishing Company, Dallas, Texas

• Clay, H. et al. 1987, Tropical shrubs, University Press of Hawaii, Honolulu

• Genders, R. 1978, Scented flora of the world, Robert Hale Publishing, London & St. Martin's Press, New York

• Kennard, W. C. & Winters, H. F. 1960, Some fruits and nuts for the tropics, Miscellaneous Publication No. 801, U.S. Department of Agriculture, Federal Experimental Station, Mayaguez, Puerto Rico

• Little, E. L. 1974, Trees of Puerto Rico and the Virgin Islands, Vol. 2, United States Department of Agriculture (USDA), Washington D.C.

• 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

• Roecklein, J. C & Leung, P.S. 1987, A Profile of economic plants, Transaction Books, New Brunswick, New Jersey

• Seidemann, J. 2005, World spice plants: economic usage botany taxonomy, Springer-Verlag, Berlin

• Standley, P. C. 1920, Trees and shrubs of Mexico, Government Printing Office (GPO), Washington D.C.

Articles, Journals, Reports and Working Papers

• Dagar, J. C. & Singh, G. 2007, Biodiversity of Saline and Waterlogged Environments: Documentation, Utilization and Management, NBA Scientific Bulletin, (9), 78.

• Morton, J. F. 1976, Pestiferous spread of many ornamental and fruit species in south Florida. In Proceedings of the Florida State Horticultural Society (Vol. 89, pp. 348-353).