 Twentieth century chemical analysis found that both nicotine and nornicotine, a drug four times as toxic as nicotine, are usually present in "Duboisia hopwoodii", and the concentrations of these chemicals can vary widely.In one study, specimens of "duboisia hopwoodii" from Western Australia and western Queensland were found to contain mainly nicotine while the active constituent of South Australian and central Australian "Duboisia hopwoodii" was predominantly the more toxic nornicotine.It has been proposed that these variations may be due to differences in rainfall, harvest season and soil salinity and acidity.