Distribution of 14C-glyphosate [N-(phosphonomethyl)glycine] in chemically treated and physically manipulated common milkweed [Asclepias syriaca (L.) ♯ ASCSY] was studied in greenhouse and growth chamber experiments. Pretreatment with glyphosate at 0.6 and 1.1 kg ae/ha 3 days prior to 14C-glyphosate application to leaves reduced the concentration of 14C recovered from shoots and leaves above the 14C-glyphosate-treated leaves but had no influence on the concentration of 14C in proximal root buds. Partial removal of the shoot and root prior to the application of 14C-glyphosate increased bud respiration and the concentration of 14C in the proximal root buds. Proximal root buds treated with 1 mM of 6-benzyl-aminopurine (BAP) for 6 days (3 days prior to application of 14C-glyphosate) contained seven times more 14C/mg than root buds of BAP-untreated plants, suggesting that dormant buds could be chemically stimulated to accumulate higher concentrations of glyphosate. BAP-treated buds were killed by foliar applications of glyphosate at 1.1 kg/ha, indicating that proximal root buds can be stimulated to acquire lethal concentrations of glyphosate.