We have treated the taxon Dysphania anthelmintica (L.) Mosyakin & Clemants as a distinct species here, though it is obviously very closely related to Dysphania ambrosioides and is very often treated as no more than a variety or even as a synonym in many modern treatments. However, it is said to be a form with more effective medicinal properties and so we are keeping it distinct here[].

Common Name: Mexican Tea

General Information

Dysphania ambrosioides is an erect, often very-branched, strong-smelling annual or short-lived perennial plant growing about 1 metre tall[].
The plant is a popular and very effective vermifuge, as well as having many other medicinal properties. Prior to the introduction of synthetic compounds the plant was widely cultivated for the control of hookworms and roundworms and it is still often grown for medicinal and culinary use, especially in its native Mexico. Dysphania anthelminticum, often treated as a variety or a synonym of this species, is more active medicinally and is the form most often cultivated for its vermicidal activity[, ].
The plant has escaped from cultivation and become widely naturalized throughout the tropics and warm temperate zones of the world[].

Known Hazards

The essential oil in the seed and flowering plant is highly toxic. In excess it can cause dizziness, vomiting, convulsions and even death[, ]. The plant can also cause dermatitis or other allergic reactions[].
The leaves and seeds of all members of this genus are more or less edible. However, many of the species in this genus contain saponins, though usually in quantities too small to do any harm. Although poisonous, saponins also have a range of medicinal applications and many saponin-rich plants are used in herbalism (particularly as emetics, expectorants and febrifuges) or as sources of raw materials for the pharmaceutical industry. Saponins are also found in a number of common foods, such as many beans.
Saponins have a quite bitter flavour and are in general poorly absorbed by the human body, so most pass through without harm. They can be removed by carefully leaching in running water. Thorough cooking, and perhaps changing the cooking water once, will also normally remove most of them. However, it is not advisable to eat large quantities of raw foods that contain saponins.
Saponins are much more toxic to many cold-blooded creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish and make them easy to catch[].
The plants also contain some oxalic acid, which in large quantities can lock up some of the nutrients in the food. However, even considering this, they are very nutritious vegetables in reasonable quantities. Cooking the plant will reduce its content of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[].

Botanical References

, ,

Range

S. America - Argentina, Paraguay, Bolivia, Peru, Colombia, Venezuela, the Guyanas; C. America - Panama to Mexico; southern N. America.

Habitat

Mainly found on dry wasteland and cultivated ground[, ]. River bottoms, dry lake beds, flower beds, waste areas; at elevations up to 700 metres in southern N. America[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual/Perennial
Height	1.00 m
Pollinators	Wind
Cultivation Status	Cultivated, Wild

Cultivation Details

Dysphania ambrosioides is a plant of the tropics and subtropics, where it is found at elevations up to 1,500 metres. It grows best in areas where annual daytime temperatures are within the range 15 - 22°c, but can tolerate 4 - 31°c[]. It can be killed by temperatures of -1°c or lower[]. It prefers a mean annual rainfall in the range 800 - 1,500mm, but tolerates 300 - 4,200mm[].
An easily grown plant, succeeding in most soils but disliking shade[, ]. It prefers a moderately fertile soil[]. Prefers a pH in the range 6.5 - 7.5, tolerating 5 - 8.7[].
Plants are annuals or short-lived perennials[]. They are not very cold-hardy and so are best grown as annuals in the temperate zone[]. Plants have often self-sown freely in our Cornish trial grounds (hardiness zone 8), but the seed often germinates in the autumn and then does not manage to survive the winter[].
The bruised leaves emit an unpleasant foetid odour[].

Edible Uses

Leaves - cooked[]. The tender leaves are sometimes used as a potherb[]. Used as a condiment in soups etc[, , ], they are said to reduce flatulence if eaten with beans[]. The leaves have a rank taste due to the presence of resinous dots and sticky hairs[]. The raw leaves should only be eaten in small quantities, see the notes above on toxicity.

Seed - cooked[, ]. The seed is small and fiddly, it should be soaked in water overnight and thoroughly rinsed before it is used in order to remove any saponins.

An infusion of the leaves is a tea substitute[].

Medicinal

Mexican tea is a Central American herb that has been used for centuries to expel parasitic worms from the body[]. The seed, or the essential oil obtained from the seed and flowering stem is used for this, though all parts of the plant are used medicinally. The plant, especially the essential oil, is toxic in larger doses and so should be used with care and preferably under the direction of a skilled practitioner[, ]. This remedy should not be prescribed for pregnant women[]. See also the notes above on toxicity.

Until fairly recently, this was one of the most commonly used vermifuges, though it has now been largely replaced by synthetic drugs[]. The seed, or the essential oil, was used[]. It is very effective against most parasites, including the amoeba that causes dysentery, but is less effective against tapeworm[, ]. Fasting should not precede its use and there have occasionally been cases of poisoning caused by this treatment[].
The essential oil is used externally to treat athlete's foot and insect bites[, ]. This is at its highest concentration in the flowering stems before seed is set, these contain around 0.7% essential oil of which almost 50% is the active vermifuge ascaridol[]. The essential oil is of similar quality from plants cultivated in warm climates and those in cool climates[].

The whole plant is analgesic, antiasthmatic, carminative, febrifuge, stomachic and vermifuge[, , , , , , ]. An infusion can be used as a digestive remedy, being taken to settle a wide range of problems such colic, diarrhoea and stomach pains; it is also used to treat conditions such as coughs, fevers and internal haemorrhages[, ]. The leaves are added in small quantities as a flavouring for various cooked bean dishes because their carminative activity can reduce flatulence[].
Externally, it has been used as a wash for haemorrhoids, as a poultice to detoxify snake bites and other poisons and is thought to have wound-healing properties[]. The macerated leaves and flowers are mixed with a pinch of salt, and used as a poultice for treating persistent sores[].

The essential oil is high in ascaridol, a nematocidal terpene peroxide which is active against ascaris, worms and ankylostomes[].

Other Uses

The plant is used as a fumigant against mosquitoes and is also added to fertilizers to inhibit insect larvae[].
Gold/green dyes can be obtained from the whole plant[].

Propagation

Seed - whilst it can be sown in situ in mid to late spring, we have had better results by sowing the seed in a cold frame in early spring. Put a few seeds in each pot and thin to the best plant if necessary. Germination rates are usually very good and the seedlings should appear within a few days of sowing the seed. Plant out in late spring, after the last expected frosts.