The novel iminosugar (1R,2S,3R,5R,8aR)-3-(hydroxymethyl)-5- methyloctahydroindolizine-1,2-diol (steviamine) was isolated from leaf material of Stevia rebaudiana and leaves and bulbs of Veltheimia capensis. This is the first report of an indolizidine iminosugar alkaloid from the Asteraceae and Hyacinthaceae. Steviamine may occur in some Stevia products and influence taste. © 2010 Phytochemical Society of Europe.