Swanson Mullein Leaf Extract 250mg 60 CapsSwanson Mullein Leaf Extract 250mg 60 Caps About Vitamins. co. nz Swanson Mullein Leaf Extract Swanson Mullein Leaf Extract capsules contain a standardized 4: 1 extract of pure mullein leaf. Dioscorides, the ancient Greek pharmacologist who wrote the original Materia Medica, is believed to be the first to employ this herb traditionally used for respiratory support. This remains its primary use today, and herbalists from China to California still