Substitute for Epazote?

I have a recipe that calls for epazote and I need to know if I can substitute something else for it. I can't find it in the market. What does epazote taste like?

Epazote is a strong flavoured, unpleasant smelling herb, native to Latin America, commonly used in Mexican, Central American and Caribbean cooking. It can sometimes be found dried in Latin markets, but due to its pungent aroma has not caught on in North America. If you let me know what the recipe includes, I may be able to suggest another herb.
Epazote is often found in bean dishes and is felt to have an anti-flatulence effect. It is also called pigweed, or worm weed (used to be given to people to cure hookworms).