Family: Chenopodiaceae
Genus: Chenopodium
Species: ambrosioides
Common Names: Erva-de-Santa Maria,  Epazote,  Wormseed,  Apasote,  Chenopode,  Feuilles A Vers,  Herbe A Vers,  Meksika Cayi,  Paico,  Pazote,  Semen Contra,  Semin Contra,  Simon Contegras

Here are more synonyms I found: pharm Herba,  Chenopodii ambrosioidis,  Welriekende ganzenvoet,  Amerikaans wormzaad,  Wormkruid,  Wormzaad,  Mexican tea,  West Indian goosefoot,  Jerusalem parsley,  Hedge mustard,  Sweet pigweed,  Saitruunasavikka,  Mexicanischer Traubentee,  Mexicanisches Teekraut,  Jesuitentee,  Kadavoma,  Katuayamodakam,  Sitronmelde,  Komosa pizmowa,  Mastruz,  Yerba de Santa Maria.

Used plant part: Leaf and flowers of epazote.

Leaves. They are best used fresh, but since the fresh herb is available only for those with their own garden, the dried herb is also common. Its aroma is still satisfactory. The seeds contain even more essential oil (about 1%) and are chiefly used because of their vermifuge powers (see below).

Plant family: Chenopodiaceae (goose-foot family).

Main constituents: Essential oil with ascaridol (up to 70%), limonene and p-cymene, furthermore numerous other monoterpenes and monoterpene derivatives (alpha-pinene, myrcene, p-cymene, terpinene, thymol, campher and trans-isocarveol).

Ascaridol is rather an uncommon constituent of spices; another plant owing much of its character to this monoterpene peroxide is boldo.

Origin: The plant is indigenous in Central and Southern Mexico, but is today a common neophyte in Europe and the U.S.

Etymology: The English genus name, goose-foot, is a translation of the scientific genus name Chenopodium: Greek che?n "goose" and po?s "foot"; it is motivated by the the three-lobed leaf shape characteristic of several plants belonging to this group. Mexican origin or association with missionary orders (e.g., the Jesuits) gave rise to several of the popular names in English and German. A very closely related variety (var. anthelmitica) is cultivated in the Southern States of the US for its potency against intestinal worms; thus the name wormseed for the plant. To prevent confusion, the variety used in the kitchen (var. ambrosioides) is usually called epazote in English. This name is taken from Nahuatl, the tongue spoken by the Aztecs before the arrival of the Spanish; it is still a minority language in Mexico and in use among the Indios living around Mexico City. The name is due to the strong smell of the herb, which many find disagreeable (epatl "skunk" and tzotl "sweat").

Epazote (flowering tip) Epazote's strong taste is characteristic of the Mayan cuisine in the South of Mexico and Guatemala. Center of epazote usage in Mexico is the Yucatan peninsula. The herb is used fresh in soups, salads and meat dishes; it appears in the recipe for mole verde, a Mexican herb sauce (see Mexican pepper-leaf). The most common usage is, however, in bean dishes, especially Mexican refried black beans (frijoles refritos). These are basically pinto beans, which are cooked with epazote and other spices (garlic, onion, cumin and dried Mexican chiles and/or paprika). After cooking, they are fried in some pig lard until a smooth puree. Refried beans are often served in Tex-Mex-style restaurants. The dried herb is considered inferior to the fresh one, but outside Central America and the southern parts of the US, fresh epazote may be hard to find. A common substitute are coriander or long coriander leaves, even in Mexico.

Epazote - Wormseed Link

Aztec Use of Epazote

Augments the secretion of all intestinal glands,  increases bile,  favors the expulsion of intestinal parasites and favors menstruation.
CAUTION if pregnant or if hepatic or renal disease is present!
May be used even if pregnant in small amounts with food since only half a leaf is used for a pound of beans.