Chenopodium ambrosioides L.

Mexican Tea, Epazote, Wormseed

Chenopodium ambrosioides plant

Family - Chenopodiaceae

Habit - Annual forb with distinct odor.

Stems - Spreading to ascending, to 1 m, usually much branched, with sparse to moderate sessile yellowish glands, sometimes tinged or striped with red.

Chenopodium ambrosioides stemGlabrous stem.

Chenopodium ambrosioides stemPubescent stem.

Leaves - Simple, sessile (uppermost) to long-petiolate (lowermost). Leaf blades mostly 5-14 cm long, those of well-developed leaves mostly 2-5 times as long as wide, linear (uppermost leaves) to oblong, lanceolate, or ovate, bluntly to sharply pointed at the tip, rounded or angled at the base, entire to irregularly lobed, yellowish green to green and herbaceous in texture, the margins often also somewhat wavy or with shallow, irregular, narrow teeth, the surfaces lacking hairs and mealiness, but with sparse to moderate, sessile, yellowish resin glands. Venation noticeably branched, often with 3 main veins from the base.

Chenopodium ambrosioides leavesLeaves.

Inflorescence - Axillary and terminal spikes, the terminal ones sometimes arranged into small panicles, the spikes relatively short and dense, with small clusters of flowers. Flowers not all maturing at the same time.

Chenopodium ambrosioides infructescenceInfructescence.

Flowers - Calyx 5-lobed to below the midpoint, covering the fruit at maturity, the lobes 0.7-1.0 mm long, ovate, bluntly pointed at the tip, flat to rounded dorsally, glabrous or with sparse to moderate, short, fine, nonglandular hairs. Stamens 5. Stigmas 3.

Chenopodium ambrosioides flowersFlowers.

Fruits - 0.6-1.0 mm long, ovoid, the seeds positioned horizontally or vertically, the wall thin, papery, and somewhat translucent, smooth to finely wrinkled, easily separated from the seed. Seeds reddish brown to dark brown, shiny, smooth to faintly wrinkled, rounded along the rim.

Chenopodium ambrosioides fruitsFruits.

Flowering - July - November.

Habitat - Crop fields, river banks, dumps, fields, railroads, roadsides, open disturbed areas.

Origin - Native to tropical America.

Lookalikes - Numerous species of Chenopodium and Amaranthus. As a group these are notoriously difficult to identify to species.

Other info. - This aromatic species can be found scattered throughout most of Missouri, and occurs in most states within the continental U.S. Among the Chenipodes it is relatively easy to identify due to its pronounced scent and conspicuously and coarsely toothed leaves. The plant is normally glabrous but pubescent individuals are not uncommon.

Many sources list "Mexican tea" as a common name for this plant, but in culinary usage a more common term is "epazote." It has long been used in Mexican culture as an herb to flavor beans and other dishes, and is believed to reduce flatulence. The essential oil ("wormseed oil") was also used to combat intestinal parasites. The oil contains a compound called ascaridole, which is a highly unusual terpenoid cyclic peroxide. In high concentration this compound, like most organic peroxides, is explosive. It is apparently the component responsible for the anthelmintic (anti-worm) properties of wormseed oil. However, the oil also has numerous adverse and toxic side effects which argue strongly against its medicinal use. There is evidence that these toxicities derive from more than one constituent, and safer and more effective modern anthelmintic treatments are available. Ascaridole is also a primary contributor to the plant's aroma, which is variously described as resembling turpentine, kerosene, creosote, citrus, or mint.

Two varieties of the species are recognized in Missouri. These differ in the presence (var. ambrosioides) or absence (var. anthelminticum) of bracts at most nodes. A more recent synonym for the plant is Dysphania ambrosioides.

Photographs taken in Vero Beach, FL., 2-13-03, and off Lee Rd 54, Lee County, AL., 10-8-04.


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