Selenium, at concentrations exceeding 200 parts per million (ppm) (dry weight), has been found in white sweet clover voluntarily growing on beds of fly ash in central New York State. Guinea pigs fed such clover concentrated selenium in their tissues. The contents of the honey stomachs of bees foraging on this seleniferous clover contained negligible selenium. Mature vegetables cultured on 10 percent (by weight) fly ash-amended soil absorbed up to 1 ppm of selenium. Fly ashes from 21 states contained total selenium contents ranging from 1.2 to 16.5 ppm. Cabbage grown on soil containing 10 percent (by weight) of these fly ashes absorbed selenium (up to 3.7 ppm) in direct proportion (correlation coefficient r = .89) to the selenium concentration in the respective fly ash. Water, aquatic weeds, algae, dragonfly nymphs, polliwogs, and tissues of bullheads and muskrats from a fly ash-contaminated pond contained concentrations of selenium markedly elevated over those of controls.