When I think of Chenopodium, mostly I think of all the weeds, like pig's weed, or the almost weeds but useful herbs such as lamb's quarters, or the newly re-discovered grains such as quinoa. Epazote is an almost weed, since if it self sows all I can say is 'Look out!' but it is such an indispensable ingredient in Mexican cooking that it is well worth the headache. Another common name for this plant is wormseed, and it typically is used for expelling worms. It is a wonderful digestive remedy, and is also used in the treatment of spasmodic coughing.
Epazote is grown as a perennial in Sunset Zones 9 - 24 (USDA zone 10), but is considered an annual eleswhere. Prune it back to the roots at the end of winter. Grow in full sun and maintain on the dry side.