Amanita muscaria var. formosa, known as the yellow orange fly agaric, is a hallucinogenic and poisonous basidiomycete fungus of the genus Amanita. This variety, which can sometimes be distinguished from most other A. muscaria by its yellow cap, is a European taxon, although several North American field guides have referred A. muscaria var. guessowii to this name. American mycologist Harry D. Thiers described a yellow-capped taxon that he called var. formosa from the United States, but it is not the same as the European variety.