Common name: Oiticica

Oiticica is an industrial oil-producing tree originating in Brazil, where it occurs in seasonally flooded river valleys in the dry Caatinga region, situated in the northeast of the country.

It is a small to medium-sized evergreen tree up to 15 m (50 ft) tall, with a straight or forked trunk supporting a dense, low-branching round or umbrella-shaped crown. The bark is rough, grey-brown and flaking. 

Leaves are elongated oval, up to 15 cm (6 in) long and alternately arranged along thin branchlets in a tightly packed crown, casting a deep shade over the ground beneath. 

Flowers are yellow, small and insignificant, bisexual and borne in loosely-branched clusters at the ends of the branches. They bloom in the dry season, coinciding with spring in its native range. Fertilised flowers are followed by oval green fruit, 3 to 6 cm (1.2 to 2.4) long, with thin pulp surrounding a single seed.

Use

The seed kernel contains up to 60% of a pale yellow, viscous oil traded as 'Oiticica Oil'. It is a drying oil, which means it hardens on exposure to air, forming, in this case, a solid cream-coloured fat. When applied thinly to surfaces, it forms a hard film, which has led to its use in paints, varnishes and other protective coatings, particularly as a substitute for Tung Oil (from Vernicia fordii).  

When mature, the fruit fall to the ground, where they are collected. A single tree yields, on average, 130 kgs (287 lbs) of fruit per year, but there are reports of exceptional trees yielding up to 500 kgs (1100 lbs). The tree, however, only starts to flower and fruit when about ten years old.

It is sometimes cultivated as a street or landscape tree due to its compact size, dense evergreen foliage and wide-spreading crown, which gives shade from the hot sun.

Climate

Grows naturally in sub-humid tropical climates, generally areas with annual lows of 20 to 25°C, annual highs of 30 to 35°C, annual rainfall of 600 to 1700 mm and a dry season of 5 to 8 months.

Growing

New plants are usually raised from seed, which lose their viability quickly. 

Performs best on free-draining loam and sand soils of a moderately acid to slightly alkaline 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 drought and seasonal flooding. 

Problem features

It was introduced long ago into Trinidad and other regions with suitable growing conditions. Still, there does not appear to be any records of it anywhere as a problem weed or invasive species.

Books

• Duke, J. A. 2001, CRC handbook of nuts. CRC Press, Boca Raton, Florida

• Hill, A. F. 1952, Economic botany : a textbook of useful plants and plant products, 2nd ed, McGraw-Hill, New York

• Jamieson, G. S. 1943, Vegetable fats and oils : their chemistry, production, and utilization for edible, medicinal and technical purposes, 2d ed, Reinhold, New York

• Janick, J., & Paull, R. E. 2008, The encyclopedia of fruit & nuts, CABI Publishing, Wallingford, Oxfordshire

• Mors, W. B & Rizzini, C. T. 1966, Useful plants of Brazil, Holden-Day Publishing, San Francisco, California

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

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

• Williams, R. O. & Freeman, W. G., 1951, The useful and ornamental plants in Trinidad and Tobago, Rev. 4th ed., Government Printer, Trinidad

Articles, Journals, Reports and Working Papers

• Kirmse RD, Pfister JA, Vale LV, Queiroz JS. Woody plants of northern Ceará Caatinga. In: Small Ruminant/CRSP Technical Report. Logan, Utah: Utah State University; 1983; p. 150; Series No. 14