Common name: East Indian Walnut

East Indian Walnut, or Siris, as it's known in India, is a deciduous timber, fodder, and landscape tree native to the Indian subcontinent and Southeast Asia. Its natural range extends from Pakistan through India to Bangladesh and Burma.

In native forests, it may reach up to 30 m (100 ft) tall with a straight trunk and narrow crown. It is typically 10 to 20 m (30 to 60 ft) tall on open sites, with a short trunk supporting a large, rounded, wide-spreading crown. The bark is grey-brown, starts smooth on young trees, and becomes fissured and rough with age.

Leaves are up to 25 cm (10 in) long and twice-feathered, with deep green, oblong leaflets arranged in pairs along each leaf branch. They fall from the tree during the dry season, leaving the branches bare until the rainy season, when new leaves emerge and grow to fill them out again.

The flowers resemble powder puffs with long greenish filaments and are sweetly fragrant. They bloom when the dry season transitions to the rainy season, coinciding with new leaf growth.

Fertilised flowers develop into flat, papery seedpods that turn light grey-brown when mature and persist on the tree for many months, far into the next dry season.

Darwin, Australia

Seedpod

Material uses

Hardwood - Wood weight, durability, and overall quality vary considerably among trees with different growth rates; slow-growing trees generally produce heavier, more durable, higher-quality wood than fast-growing trees. In the tropics, moisture availability strongly influences growth rates, which generally increase with rainfall, so wood density and natural resistance do vary considerably, ranging from 500 to 800 kg per cubic meter (31 to 50 lb per cubic ft) and from non-resistant to moderately resistant.

Timber and lumber - Well-formed logs are sawn into planks. The heartwood is attractive, resembling brown walnut with its characteristic black and grey streaks

Flooring and decking - Used mainly for flooring.

Furniture and cabinets - Also used for furniture and cabinets.

Joinery and millwork - Also used for joinery work.

Decorative veneer - Selected logs are sliced for decorative veneer.

Firewood - Small-diameter lengths and branchwood are cut for firewood.

Charcoal - Also used to make charcoal.

Livestock feed - The fresh leaves and young seedpods are palatable to ruminants and are used as a livestock feed, with a reported crude protein content of about 20% of their dry weight.

Environmental uses

Crop shading - Albizia lebbeck is commonly planted to shade coffee (Coffea arabica) and tea (Camellia sinensis).

Erosion control - Also planted to prevent soil erosion.

Nitrogen-fixing - Its nitrogen-fixing abilities, along with its tolerance to adverse growing conditions, support these environmental services.

Shade tree - Also cultivated in gardens and landscapes for the shade it provides.

Flowering ornamental - Also valued for its showy, fragrant flowers.

Climate

Grows naturally in sub-humid to humid subtropical and tropical climates, generally areas with annual lows of 16 to 25°C, annual highs of 27 to 37°C, annual rainfall of 400 to 2500 mm and a dry season of 2 to 8 months, extending to 12 months with irrigation or groundwater. However, it develops best as a timber tree in areas with annual rainfall of 1300 mm or more.

Growing

New plants are usually started from seed, which is pretreated before sowing by immersing it in boiling water for a few seconds, then allowing it to cool. It performs best on moist-to-dry, free-draining loam and sand soils of a slightly acid to alkaline nature, generally with a pH of 5.0 to 8.5. It tolerates drought, seasonal flooding, soil salinity, and limestone soils.

Problem features

The seedpods are produced in large quantities and are easily dispersed by wind and water. It is listed in multiple reference publications as a serious weed. The Hawaii Pacific Weed Risk Assessment project (HPWRA) and the IFAS Assessment of Non-Native Plants in Florida's Natural Areas assess it as a high weed risk for Hawaii and Florida, respectively. Root-suckering also contributes to its weediness.

Pollen released by flowers is reported to cause hay fever in some people, and dust from sawn wood irritates the nasal passages.

Books

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

• Allen, O. N. & Allen, E. K. 1981, The Leguminosae : a source book of characteristics, uses, and nodulation, University of Wisconsin Press, Madison, Wisconsin

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

• Chevallier, A. 2000, Encyclopedia of herbal medicine, 2nd American ed., Dorling Kindersley, New York

• Chudnoff, M. 1984, Tropical timbers of the world, Forest Service, U.S. Department of Agriculture (USDA), Washington, D.C.

• Dey, S.C. 1996, Fragrant flowers for homes and gardens, trade and industry, Abhinav Publications, New Delhi, India

• Doran, J. C & Turnbull, J. W. 1997, Australian trees and shrubs : species for land rehabilitation and farm planting in the tropics, 2nd ed, Australian Centre for International Agricultural Research (ACIAR), Canberra, Australian Capital Territory

• Duke, J. A. 1983, Handbook of energy crops (unpublished), Center for New Crops & Plants Products, Purdue University, West Lafayette, Indiana

• Fawcett, W. 1891, Economic plants, An index to economic products of the vegetable kingdom in Jamaica, Jamaica Government Printing Establishment, Kingston

• Francis, J. K. 1998, Tree species for planting in forest, rural, and urban areas of Puerto Rico, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, Río Piedras, Puerto Rico

• Francis, J. K. and Liogier, H. A. 1991, Naturalized exotic tree species in Puerto Rico, General technical report SO-82, USDA Forest Service, Southern Forest Experiment Station, New Orleans

• Francis, J. K. et al. 2000, Silvics of Native and Exotic Trees of Puerto Rico and the Caribbean Islands, Technical Report IITF-15, USDA Forest Service, Rio Piedras, Puerto Rico

• Gohl, B. 1981, Tropical Feeds : feed information summaries and nutritive values (Revised edition), Food and Agriculture Organization of the United Nations (FAO), Rome

• Hall, N. 1972, The use of trees and shrubs in the dry country of Australia, Australian Government Publishing Service, Canberra, Australian Capital Territory

• Hocking, D. 1993, Trees for drylands, International Science Publisher, New York

• Howes, F. N. 1949, Vegetable gums and resins, Chronica Botanica Company, Waltham, Massachusetts

• Jensen, M. 1999, Trees commonly cultivated in Southeast Asia : an illustrated field guide, 2nd ed., Food and Agricultural Organisation of the United Nations (FAO) Regional Office for Asia and the Pacific (RAP), Bangkok

• Krishen, P. 2006, Trees of Delhi : a field guide, Dorling Kindersley Publishers, Delhi

• Letourneux, C. 1957, Tree planting practices in tropical Asia, Food and Agriculture Organization of the United Nations (FAO), Rome

• Liegel, L. H. 1987. A technical guide for forest nursery management in the Caribbean and Latin America, U.S. Dept. of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans

• Luna, R. K 1996, Plantation trees, International Book Distributors, Dehradun, Uttarakhand

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

• Nair, P. K. R. 1993, An introduction to agroforestry, International Centre for Research in Agroforestry (ICRAF), Kluwer Academic Publishers, Dordrecht

• National Research Council (Board on Science and Technology for International Development) 1980, Firewood crops : shrub and tree species for energy production (Volume 1), The National Academies Press, Washington D. C.

• Parrotta, J. A. 2001, Healing plants of peninsular India, CABI Publishing, Wallingford, Oxfordshire

• Porter, T. 2012, Wood : identification & use, Compact edition, Guild of Master Craftsman Publications, Lewes, East Sussex

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

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

• Schubert, T. H. 1979, Trees for urban use in Puerto Rico and the Virgin Islands. U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans

• Singh, R. V. 1982, Fodder trees of India, Oxford & IBH Publishing Company, New Delhi

• Vázquez, Y. C. 1999, Potentially valuable Mexican trees for ecological restoration and reforestation, Institute of Ecology, Database SNIB-REMIB-CONABIO, Project J084, Mexico

• Webb, D. B. 1984, A Guide to species selection for tropical and sub-tropical plantations, 2nd ed., Unit of Tropical Silviculture, Commonwealth Forestry Institute, University of Oxford, Oxfordshire

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).

• Morton, J.F. 1964, Honeybee Plants of South Florida, Proceedings of the Florida State Horticultural Society, Vol 77:415-436.

• Nair, P. K. R., Fernandes, E. C. M., & Wambugu, P. N. (1985). Multipurpose leguminous trees and shrubs for agroforestry. Agroforestry systems, 2(3), 145-163.