In New Zealand, large-scale control of introduced possums ( Trichosurus vulpecula) and rabbits (Oryctolagus cuniculus) is based on aerial application of baits containing the toxin sodium monofluoroacetate (1080). The high solubility of 1080 has caused concerns about the environmental effects of 1080 leaching from baits into soil and waterways (Livingstone 1994). Sodium monofluoroacetate which has leached into soil may be absorbed by plants (Atzert 1971; Rammel & Fleming 1978). Cabbage (Brassica oleracea capitata) has been shown to systemically accumulate 1080 through its roots, and subsequently become toxic to aphids (Negherbon 1959). Herbivores may be at risk of secondary poisoning if they consume plants which have taken up 1080 that has leached from bait. Depending on the period of time 1080 persists within plant tissues, plants could remain toxic to herbivores after the risk of primary poisoning had gone, i.e., after baits had degraded and become non-toxic. We have investigated the potential risks of 1080 poisoning to herbivorous species by determining the uptake and persistence of 1080 in two plant species, the native New Zealand broadleaf (Griselinia littoralis), a dicotyledon, and perennial ryegrass ( Lolium perenne), a monocotyledon. MATERIALS AND METHODS