Caloboletus calopus, commonly known as the bitter beech bolete or scarlet-stemmed bolete, is a fungus of the bolete family, found in Asia, Northern Europe and North America. Appearing in coniferous and deciduous woodland in summer and autumn, the stout fruit bodies are attractively coloured, with a beige to olive cap up to 15 cm (6 in) across, yellow pores, and a reddish stipe up to 15 cm (6 in) long and 5 cm (2 in) wide. The pale yellow flesh stains blue when broken or bruised.