Common name: Wild cashew

Wild cashew is a timber tree and Cashew (Anacardium occidentale) relative originating in Central and South America, its natural range extending from Guatemala, through Costa Rica and Panama, to northern parts of South America. 

It grows at a moderate rate, into a large tree up to 40 m (130 ft) tall and with a straight trunk of 2.0 m (6.5 ft) diameter supporting a densely branched rounded crown. The bark is grey-brown or reddish-brown, rough with deep fissures and usually flaking on older trees.

The leaves are club-shaped, 15 to 30 cm (6 to 12 in) long, deep green, prominently veined on top and spirally arranged at the ends of the branches. They fall off the tree in the dry season to conserve water, leaving the branches mostly bare for one to two months, after which the new leaves emerge.

The flowers are small and insignificant, greenish to green-white becoming pink. They are borne in loose clusters at the ends of the branches and bloom near the end of the dry season, coinciding with new leaf growth. They release a spicy fragrance, reportedly perfuming the forest with a clove-like scent.

The fruit resembles those of cashew, with a kidney-shaped fruit up to 4 cm (1.6 in) long appendage to a false fruit and enclosing a single seed or nut. Green when young, the fruit mature to pale grey or brown about two to three months after fruit-set. 

Use

Wild cashew produces a light-weight wood, in the 300 to 450 kg per cubic meter ( 19 to 28 lbs per cubic ft) range, with low to moderate natural resistance to rot and decay. This classes it as a non-durable softwood, with poor suitability for outdoor use and heavy construction generally.

The heartwood is dark brown with a reddish-orange tinge, attractively figured and has a high lustre. Well-formed logs are sawn into planks for making furniture, boxes and crates, sliced for decorative veneer and plywood or processed into pulp for making paper.

It is reported as a honey plant, but there does not appear to be much reliable information on the honey itself, its taste, colour or crystallisation properties.

The seedlings are a potential source of rootstock for cashew grown in flood-prone areas.

Climate

Grows naturally in humid subtropical and tropical lowland to mid-elevation climates, generally areas with annual lows of 16 to 25°C, annual highs of 26 to 35°C, annual rainfall of 1200 to 4500 mm and a dry season of 5 months or less.

Although in some parts of its native range the climate is sub-humid, with than 1200 mm annual rainfall and with a distinct dry season, the trees are found next to streams, rivers or watercourses where the roots have access to water during dry periods.

Growing

New plants are usually raised from seed, which remain viable only for a couple of months under cold, dry, air-tight conditions. Performs best on free- or slow-draining clay, loam and sand soils of a moderately acid to neutral nature, generally with a pH of 5.0 to 7.5, and on sites with full to partial sun exposure. It has good tolerance to seasonal flooding and waterlogged soils.

Problem features

The wood- or saw-dust is known to cause asthma and dermatitis in some woodworkers and the raw fruit contains a very toxic, caustic oil, similar to that of cashew.

The seed may be dispersed by floodwaters or by native wild animals that eat the fruit or pseudo-fruit. However, the seed germinate poorly, or not at all, under shade and there does not appear to be any record of it as a weed anywhere in the world.

Books

• Berni, C. A & Bolza, E. & Christensen, F. J. 1979, South American timbers - the characteristics, properties and uses of 190 species, Commonwealth Scientific and Industrial Research Organization (CSIRO), Division of Building Research, Highett, Victoria, Australia

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

• Crane, E., Walker, P. & Day, R. 1984, Directory of important world honey sources, International Bee Research Association, London

• Croat, T. B. 1978, Flora of Barro Colorado Island, Stanford University Press, Stanford, California

• Echenique-Manrique, R. & Plumptre, R. A. 1990, A guide to the use of Mexican and Belizean timbers, Oxford Forestry Institute, Deptment of Plant Sciences, University of Oxford, Oxfordshire

• Gargiullo, M. B & Magnuson, B. L. & Kimball, Larry D. 2008, A field guide to plants of Costa Rica, Oxford University Press, Oxford

• Mitchell, John D. (John Daniel) & Mori, Scott A., 1941- & Mori, Scott A & Mitchell, John D 1987, The cashew and its relatives (Anacardium: Anacardiaceae), New York Botanical Garden, Bronx, N.Y., USA

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

• Record, S. J. & Hess, R. W., 1972, Timbers of the New World, Yale University Press, New Haven, Connecticut & Arno Press, New York

• 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

• Vozzo, J. A 2002, Tropical tree seed manual, U.S. Department of Agriculture (USDA), Forest Service, Washington D.C.