Common name: Epazote

Epazote is a short-lived perennial herb commonly used in Mexican cuisine.

Native to the Americas, its distribution is widespread, extending from the south-west of the United States, through Mexico and other countries in Central America to the Caribbean and South America. Nowadays, it is naturalised in many regions around the world and is a declared weed in some countries. 

A free-seeding herb with a weedy habit, it is often found growing wild on open ground with poor, thin or gravelly soil. It is typically 0.5 to 1.2 m (1.6 to 4 ft) tall with a bushy appearance and is strongly aromatic. 

The leaves are lance-shaped, dark green, on the lower parts of the plant 5 to 8 cm (2 to 3 in) long and toothed on the margins, on the upper parts much smaller and smooth-margined. 

The flowers are tiny, greenish and in small clusters that branch off of tall spikes arising at the ends of the stems. They are followed by small seedpods holding tiny black seed.

Use

The fresh young leaves and soft stems are used as a culinary herb in Mexican cooking, especially for flavouring bean and mushroom dishes but also salads, soups, sauces, seafood and meats. It has strong turpentine and camphor odours and a flavour described as bitter with mild citrus and mint notes. It is at its most flavoursome when fresh and is usually added at the end of the cooking process.

Health use

A strongly scented colourless or pale yellow oil is extracted from the leaves, stems and flowering tops by steam distillation. Know in the trade as 'Wormseed oil', it contains up to 75% ascaridole, a powerful intestinal worm expellent and has a history of use as a vermifuge, especially in the treatment of hookworm and roundworm. Nowadays, it is mostly replaced by synthetic drugs with less toxic side-effects (see below).

Climate

Grows naturally in sub-humid to humid warm temperate, subtropical and tropical climates, generally areas with annual lows of 6 to 24°C, annual highs of 17 to 35°C, annual rainfall of 300 to 4000 mm and a dry season of 9 months or less.

In usually perennial in subtropical and tropical climates but annual in climates with cold winters. 

Growing

New plants are usually started from seed. Performs best on free-draining loam and sand soils of a moderately acid to alkaline nature, generally with a pH of 6.0 to 8.0, and on sites with full to partial sun exposure.

Problem features

The plant produces a lot of seed that are easily dispersed by wind and water and germinate readily. In more than one country, it is recorded as an invasive species, a weed class reserved for the most serious weed and it is assessed as a high weed risk species for Hawaii by the Hawaii Pacific Weed Risk Assessment (HPWRA) project .

Wormseed oil is toxic in overdose and should also not be used in pregnancy. Overdoses have caused many side effects, ranging from headaches, nausea and hallucinations to gastric and central nervous system disturbances, as well as liver and kidney damage, paralysis, coma and in rare cases fatalities.

Wormseed oil is highly flammable due to its high ascaridole content (a terpene) and should be handled with caution. 

Books

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

• Arctander, S. 1960, Perfume and flavor materials of natural origin, Elizabeth, New Jersey

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

• Groom, N. 1997, The new perfume handbook, 2nd ed., Blackie Academic & Professional, London

• Khan, I. A. & Abourashed, E. A. 2010, Leung's encyclopedia of common natural ingredients : used in food, drugs and cosmetics, 3rd edition, Wiley Publishing, Hoboken, New Jersey

• Lawless, Julia 2013, The encyclopedia of essential oils : the complete guide to the use of aromatic oils in aromatherapy, herbalism, health, & well being, Conari Press, San Francisco, CA

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

• Perkins, K. D. & Payne, W. 1981, Guide to the poisonous and irritant plants of Florida, Florida Cooperative Extension Service, Gainesville, Florida

• Preedy, V. R., (editor.) 2015, Essential oils in food preservation, flavor and safety, Elsevier Ltd, Amsterdam, The Netherlands

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

• Sterling, D. 2014, Yucatán : recipes from a culinary expedition, First edition, Austin, TX University of Texas Press

• Van Wyk, B. E. 2005, Food plants of the world: an illustrated guide, 1st ed., Timber Press, Portland, Oregon

Articles, Journals, Reports and Working Papers

• Asprey, G. F. and P. Thornton, Medicinal plants of Jamaica, West Indies Medical Journal 2 (1953): 241-52