Cleaning up polluted industrial sites may not require billion-rupee government programmes. Instead, scientists suggest, plant a poplar tree. Laboratory-designed hybrids of the fast-growing tree have been found to act like 100- foot straws that suck contamination from soil and ground water. This natural cleanup is inexpensive but takes several years to complete. Still unknwon, however, is whether the chemical byproducts generated by the poplar really are less harmful, or if dilluting them in the atmosphere only creates another hazard.