Epimedium grandiflorum (large flowered barrenwort, bishop's hat) is a species of flowering plant in the family Berberidaceae, native to China, Japan and Korea.It is known as dam dâm dương hoắc In. vietnamesepimedium grandiflorum (large flowered barrenwort, bishop's hat) is a species of flowering plant in the family Berberidaceae, native to China, Japan and Korea.