Plant a forest, clean up a Superfund site. That's the idea behind phytoremediation, a technology that uses vegetation to absorb hazardous waste. The technique is old, but now there's a new twist that promises to make toxic dumping grounds green in more ways than one. British researchers have identified bacteria living in the roots of poplar trees that produce an enzyme that zaps residue from RDX, a chemical compound used by the military and industry. The scientists hope to genetically engineer the enzyme to boost the tree's ability to suck up toxic waste. So don't be surprised if you start seeing forests sprouting up on old military bases. (See the full story.)