**Chenopodium ambrosioides L. (Chenopodiaceae)**

**Epazote, Mexican Tea, Wormseed**

**Description**. Annuals or biennials, sometimes persisting longer, 2-23
dm tall, erect, with an unpleasant, often strong odor; stem branches
ascending to spreading or decumbent near the base, glandular. Leaves
alternate, lower and middle cauline ones 2-8 (24) cm long, petiolate,
blades oblong to lanceolate, margins toothed to undulate or shallowly
pinnatifid, often densely glandular, the upper ones smaller, narrower,
often with a tapered base or sessile. Inflorescences terminal or in
upper axils, spike-like, leafy, flowers in small spherical, axillary
clusters. Sepals 5, ovate, glabrous to sparsely glandular, enclosing the
fruit at maturity; corolla absent; stamens 5; ovary superior, with 2
stigmatic branches. Fruits either vertical (compressed side parallel to
floral axis) or horizontal (compressed side perpendicular to flora
axis), ca. 0.5-1 mm in diameter, with 1 seed, the outer fruit wall
peeling readily from the seed proper. Seeds dark brown to black. In
California, flowering from May to November. (Abrams 1944, Aellen and
Just 1943, Brenan 1964, Crawford and Wilson 1986, Gleason and Cronquist
1991, Munz 1959, Wahl 1954, Wilken 1993).

**Note:** Perennial forms have been called var. *suffruticosum* (Willd.)
Aellen, but no other differences are apparent (Gleason and Cronquist
1991). Other similar species include *C. multifidum*, which has a
sprawling habit, and a 3-5-toothed tubular calyx.

*Chenopodium ambrosioides* has been used extensively as a vermifuge by
native cultures in North and Central America (Moerman 1986). It has been
investigated for a number of biological properties useful in treating
intestinal worms (for which it is cultivated in Mexico and Central
America), other human diseases, and as a fungicide (e.g., Cacerse et al.
1991, Dubey and Kishore 1987, Kishore et al. 1989, Pare et al. 1993,
Peterson et al. 1989, Su 1991).

**Geographic** **distribution**. A native of subtropical America,
epazote is also widespread in most of North America except Canada and
the Pacific northwest, and has become naturalized in Mediterranean
Europe, Japan, New Zealand, southern Africa, and Hawaii (Brenan 1976,
Chapman 1991, Crawford and Wilson 1986, Furlan 1983, Gleason and
Cronquist 1991, Munz 1959, Ohwi 1965, Wagner et al. 1990, Webb et al.
1998).

Epazote was apparently first collected in California ("Salinas River")
in the 1850s (Robbins 1940) and was reported from salt marshes and waste
places as early as 1865 by Brewer et al. (1876). It is reported only
from Santa Cruz and Santa Rosa islands (Junak et al. 1997), but is
widespread throughout much of the California mainland west of the Sierra
Nevada (Anonymous 1998, Munz 1959, Wilken 1993).

**Reproductive and vegetative biology**. No literature discussing the
reproductive biology of *Chenopodium ambrosioides* was found. However,
most *Chenopodium* species are self-compatible, and wind-pollinated
(Richards 1986, Proctor et al. 1996). Seeds of *Chenopodium album* have
been reported to remain viable for as long as 1,600 years (Odum 1965).
Seed germination of epazote is apparently stimulated by light and close
proximity to the soil surface (Vazquez-Yanes and Orozco-Segovia 1990).
Water soluble extracts of vegetative parts have a significant
allelopathic effect on seed germination (Datta and Ghosh 1987).

**Ecological distribution**. Other than under cultivation, epazote has
been reported to occur on or in sandy flats, floodplains, fields, waste
places, and disturbed sites (Brenan 1976, Crawford and Wilson 1986,
Furlan 1983, Gleason and Cronquist 1991, Munz 1959, Robbins et al.
1970).

**Weed status.** *Chenopodium ambrosioides* is not considered a noxious
weed in agricultural or horticultural practice, at least at a global
level (not listed by Holm et al. 1977), nor is it considered a noxious
weed by the State Dept. of Food and Agriculture (Anonymous 1996).
However, it is listed as a weed in the United States by Lorenzi and
Jeffery (1987).

**Fungal and insect pathogens**. No literature was found that reported
*Chenopodium ambrosioides* as a host of of detrimental fungal or insect
pathogens. It is especially noteworthy that this species apparently
possesses known antifungal biochemicals (Dubey and Kishore 1987, Kishore
et al. 1989, Pare et al. 1993, Peterson et al. 1989), some of which are
also known to repel insects (Su 1991).

**Herbicide control**. No literature was found that reported herbicide
treatments specifically for epazote. Although not specifically tested,
atrazine, hexasinone, simazine, and sulfometuron are among several
herbicides recommended by Lorenzi and Jeffery (1987).

**Literature Cited**

Abrams, L. (ed.). 1944. Illustrated flora of the Pacific states. Volume
2. Polygonaceae to Krameriaceae. Stanford University Press, Stanford,
California. 635 pp.

Aellen, P. and T. Just. 1943. Key and synopsis of the American species
of *Chenopodium*. American Midland Naturalist. 30: 47-76.

Anonymous. 1996. Exotic pest plants of greatest ecological concern in
California as of August 1996. California Exotic Pest Plant Council. 8
pp.

Anonymous. 1998. California county flora database version 2, Santa
Barbara Botanic Garden and USDA National Plants Data Center, Santa
Barbara and New Orleans. URL = plants.usda.gov

Brenan, J. *Chenopodium*. pp. 92-95. In Tutin et al. (eds). Flora
Europaea. Volume 1 Lycopodiaceae to Platanaceae. Cambridge University
Press, Cambridge. 464 pp.

Brewer, W., S. Watson, and A. Gray. 1876. Geological Survey of
California. Volume 1. John Wilson, University Press, Cambridge,
Massachusetts. 622 pp.

Richards, A. 1986. Plant breeding systems. Cambridge University Press,
Cambridge, Great Britain. 529 pp.

Caceres, A., O. Cabrera, O. Morales, P. Mollinedo, and P. Mendia. 1991.
Pharmacological properties of *Moringa oleifera*. 1. Preliminary
screening of antimicrobial activity. Journal of Ethno-Pharmacology. 33:
213-216.

Chapman, A. 1991. Australian plan name index. A-C. Australian Government
Publishing Service, Canberra. 897 pp.

Crawford, D. and H. Wilson. *Chenopodium*. pp. 166-173. In Great Plains
Flora Association. Flora of the Great Plains. University of Kansas
Press, Lawrence. 1402 pp.

Datta, S. and K. Ghosh. 1987. Allelopathy in two species of
*Chenopodium* - inhibition of

germination and seedling growth of certain weeds. Acta Societatis
Botanicorum Poloniae. 56: 257-270.

Dubey, N. and N. Kishore. 1987. Fungitoxicity of some higher plants and
synergistic activity of their essential oils. Tropical Science. 27:
23-27.

Furlan, A. 1983. Flora fanerogamica da Reserva do Parque Estadual das
Fontes do Ipiranga (Sao Paulo, Brasil). 30. Chenopodiaceae. Hoehnea. 10:
38-39.

Gleason, H. and A. Cronquist. 1991. Manual of the vascular plants of
northeastern United States and Adjacent Canada. 2nd edition. New York
Botanic Garden, Bronx. 910 pp.

Holm, L., D. Plucknett, J. Pancho, and J. Herberger. 1977. The world's
worst weeds: distribution and ecology. University Press of Hawaii,
Honolulu. 609 pp.

Kishore, N., S. Dixit, and N. Dubey. 1989. Fungitoxic studies with
*Chenopodium ambrosioides* for control of damping-off in *Phaseolus
aureus* (Moong) caused by *Rhizoctonia solani*. Tropical Science. 29:
171-176

Lorenzi, H. and L. Jeffery. 1987. Weeds of the United States and their
control. Van Nostrand Company, New York. 355 pp.

Moerman, D. 1986. Medicinal plants of Native America. University of
Michigan Museum of Anthropology Technical Reports, Number 19. Volume 1.
534 pp.

Odum, S. 1965. Germination of ancient seeds: floristical observations
and experiments with archaeologically dated soil samples. Dansk Botanisk
Arkiv 24: 1-70.

Ohwi, J. 1965. Flora of Japan. Smithsonian Institution, Washington D.C.
1066 pp.

Munz, P. 1959. A flora of California. University of California Press,
Berkeley. 1681 pp.

Pare, P., J. Zajicek, V. Ferracini, and I. Melo. 1993. Antifungal
terpenoids from *Chenopodium ambrosioides*. Biochemical Systematics and
Ecology. 21: 649-653.

Peterson, G., M. Kandil, M. Abdallah, and A. Farag. 1989. Isolation and
characterisation of biologically-active compounds from some plant
extracts. Pesticide Science. 25: 337- 342.

Proctor, M., P. Yeo, and A. Lack. 1996. The Natural history of
pollination. Timber Press, Portland, Oregon. 479 pp.

Richards, A. 1978. The pollination of flowers by insects. Linnean
Society Symposium Series 6: 1-213. Academic Press, London.

Robbins, W. 1940. Alien plants growing without cultivation in
California. Agricultural Experiment Station. Bulletin 637. University of
California, Berkeley. 128 pp.

Robbins, W., M. Bellue, and W. Ball. 1970. Weeds of California.
Documents and Publications, Sacramento, California. 547 pp.

Su, H 1991. Toxicity and repellency of *Chenopodium* oil to four species
of stored- product insects. Journal of Entomological Science. 26:
178-182.

Vazquez-Yanes, C. and A. Orozco-Segovia. 1990. Ecological significance
of light controlled seed germination in two contrasting tropical
habitats. Oecologia. 83: 171- 175.

Wagner, W., D. Herbst, and S. Sohmer. 1990. Manual of the flowering
plants of Hawaii. 1853 pp.

Wahl, H. 1954. A preliminary study of the genus *Chenopodium* in North
America. Bartonia 27: 1-46.

Webb, C., W. Sykes, and P. Garnock-Jones. 1988. Flora of New Zealand.
Volume 4. Naturalized pteridophytes, gymnosperms, dicotyledons.
Department of Scientific and Industrial Research, Christchurch. 1365 pp.

Wilken, D. 1993. *Chenopodium*. pp. 506-511. In J. Hickman (ed.) The
Jepson Manual: higher vascular plants of California. University of
California Press, Berkeley. 1400 pp.