Poplar trees were found to be capable of taking up trichloroethylene (TCE) and degrading it to several known metabolic products:  trichloroethanol, trichloroacetic acid, and dichloracetic acid. Poplars were also shown to transpire TCE in measurable amounts. To eliminate the possibility that the degradation we observed was produced solely by rhizosphere organisms, axenic poplar tumor cell cultures were tested; the cultures produced the same intermediate metabolic products. When dosed with [14C]TCE, cell cultures also produced low levels of radiolabeled carbon dioxide and a labeled insoluble residue. These results show that significant TCE uptake and biotransformation occurs in poplar, which demonstrates the potential for the use of poplars for in situ remediation of TCE.

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Crown architecture, including branching pattern, branch characteristics and orientation of proleptic and sylleptic branches was studied in five poplar clones (Populus deltoides, P. trichocarpa and P. trichocarpa x P. deltoides hybrids), grown under intensive culture in the Pacific Northwest, USA. Branch characteristics measured were number, length, diameter, biomass and the angles of origin and termination. The results suggest that genotype has a major influence on crown architecture in Populus. Clonal differences in branch characteristics and branching patterns were found that resulted in striking differences in crown form and architecture. Branch angle and curvature differed significantly among clones, and among height growth increments within clones. Branch length and diameter were significantly correlated in all clones. Sylleptic branches and the considerable leaf area they carry have important implications for whole tree light interception, and thus, play a critical role in the superior growth and productivity of certain hybrid poplar clones. The considerable variation in branch characteristics implies a strong justification for including them in selection and breeding programs for Populus.