I would it guess it would depend on what toxins you're talking about and how toxic they are to plants? I don't think I would depend on plants to 'remove' toxins from the soil. If the toxins are absorbed by the plant, they will be deposited in the wood, leaves, and fruit (etc.). Unless you're willing to bag up and dispose of the garden waste, the toxins will get re-deposited in the soil. It's very unlikely you'll find a plant that will metabolize toxins into something safe.
There are studies being done on this. It is called phytoextraction. You would need to dispose of the plant matter though. Here is a link to a weblog piece I wrote and hurray! the link to the main article still works.
Oops, sorry. I guess you need the link to the weblog entry to get to the article. http://www.botanicalgarden.ubc.ca/weblog/000561.php
Looking back at the original question, rashena is probably not trying to clean up the soil, but perhaps just looking for plants that are tolerant of soils with contamination. It would be helpful to know what type of contamination was in the soil.
thank you all for your interest and comments. i am aware that the plante being used would have to be disposed of, burning the most efficient, i would assume. i read an article of ground in new york that was contaminated with toxins (the exact toxins were not mentioned), and someone suggested using certain plants to clean the area, which worked, and the plants were then burned. i have no contaminated soil at present, but the idea was fascinating, and the knowledge invaluable. so, i was just wondering if anyone knew of this practice.
The article may have been written on a closed landfill. Closed landfillls are sometimes capped then planted and used as parks. Everett Crowley Park here in Vancouver is a closed landfill. If you google Fresh Kills New York, you'll be able to read more about their project. It's really interesting. I know other local municpalities are working on similar parks. You mighta also be interesed in http://www.uvcs.uvic.ca/restore/index.aspx is a local program Restoration of Natural Systems.
Ferns often are an excelent solition to removing toxins from your soil. as well as euphorbia i believe
