Ciboria amentacea, commonly known as the catkin cup, is a species of ascomycete fungus in the family Sclerotiniaceae. It occurs is widespread in Europe and North America, where it grows on catkins of willow and alder. The species was first by Giovanni Battista Balbis in 1804 as Peziza amentacea. Karl Wilhelm Gottlieb Leopold Fuckel transferred it to Ciboria in 1870.