The absorption, translocation, and metabolism of glufosinate were investigated in three differentially susceptible weeds, Xanthium strumarium (most susceptible), Ipomoea purpurea (intermediate susceptibility), and Commelina diffusa (least susceptible). Xanthium strumarium absorbed about three times more 14C-glufosinate than Ipomoea purpurea and about six times more 14C-glufosinate than Commelina diffusa. Translocation of the applied herbicide out of the treated leaf was low. No evidence of glufosinate metabolism, either in the treated leaves or roots, was found when the extracts were separated by HPLC.